I forgot how to add and subtract mixed # fractions. How do you do it?

ex) 3/7+5/6=1 11/42- How did they get this answer??

ex) 5 6/13-2 8/13=2 11/13- How did they get this answer??

ex) 3/7+5/6=1 11/42
You need to find a common denominator when adding or subtracting fractions.

3/7 = 18/42
5/6 = 35/42

18/42 + 35/42 = 53/42 = 1 11/42

ex) 5 6/13-2 8/13=2 11/13
5 6/13 = 4 19/13

4 19/13 - 2 8/13 = 2 11/13

  1. 👍 0
  2. 👎 0
  3. 👁 171
asked by Mack
  1. It's easy to add and subtract like fractions, or fractions with the same denominator. You just add or subtract the numerators and keep the same denominator. The tricky part comes when you add or subtract fractions that have different denominators. Since only like fractions can be added or subtracted, we first have to convert unlike fractions to equal like fractions. We want to find the smallest, or least, common denominator, because working with smaller numbers makes doing the math easier. The least common denominator, or LCD, of two fractions is the smallest number that can be divided by both denominators. Rewrite the fractions as equivalent fractions with the LCM as the denominator. Then add or subtract only the numerators and keep the denominator the same. For mixed numbers, you add the whole numbers and add the fractions separately, or change them to improper fractions then find the LCD. Then, add or subtract and simplify.
    I prefer to write the multiples of both denominators until I find a common multiple.
    Let’s solve the problem: ¾ + 1/6
    Simply start writing all the multiples of both denominators, beginning with the numbers themselves. For example: Multiples of 4 are 4, 8, 12, 16, and so on (because 1 × 4=4, 2 × 4=8, 3 × 4=12, 4 × 4=16, etc.). The multiples of 6 are 6, 12, …-- wait, stop! That's the number we're looking for, 12, because it's the first one that appears in both lists of multiples. It's the least common multiple, which we'll use as our least common denominator.
    Now that we have our least common denominator, we can make equal like fractions by multiplying the numerator and denominator of each fraction by the factor needed. We multiply 3/4 by 3/3, since 3 times 4 is 12, and we multiply 1/6 by 2/2, since 2 times 6 is 12. This gives the equal like fractions 9/12 and 2/12. Now we can add the numerators, 9 + 2, to find the answer, 11/12. 11/12 is its simplest form, because we cannot divide it by 2 evenly and 11 is a prime number.

    1. 👍 0
    2. 👎 1
    posted by Dawson

Respond to this Question

First Name

Your Response

Similar Questions

  1. basic math

    In my book A bread piece calls for 3 1/4 cups of flour if you only have 2 1/8 cup. How much more flour is needed? 3 1/4 -2 1/8= 13/4 - 17/9 how does it equal 13/4 can someone show me that part? I thought I knew how to subtract

    asked by chrissy on August 6, 2007
  2. math

    Fractions and mixed numbers are often used in everyday life. Discuss a real-life example in which you would need to add, subtract, multiply, or divide fractions or mixed numbers, and show the math

    asked by Jennifer on January 13, 2014
  3. math ( subtracting fractions)

    12 1/4- 4 1/8 When you add or subtract fractions, you have to have the same denominator. In this problem you have to change 1/4 to 2/8. Then subtract the fraction and then subtract the whole number. Please post your answer and

    asked by Sophia on January 31, 2007
  4. Math

    Shelly and Marcom are selling popcorn for their music club. Each of them received a case of popcorn to sell. Shelly has sold 7/8 of her case and Marcon has sold 5/6 of his case. Which of the following explains how to find the

    asked by Jerald on November 8, 2012
  5. Math

    Everett is reading a book for his language arts class. He read 1/3 of the book on Saturday, 3/8 of the book on Sunday and 1/4 of the book on Monday. Which procedure can Everett use to find the total fraction of the book he has

    asked by Jerald on November 8, 2012
  6. math(adding mixed fractions)

    please help me with (addition mixed fractions)i cant get it!!! ---addition with mixed numbers--- 1.which of the following is not true for adding mixed numbers? A.the denominators of the fractions must be the same in order to add

    asked by matt on December 1, 2013
  7. math

    i need some to explain how to turn 1.05 into a fraction Do you know how to add fractions? 1 + 0.05 equals 1.05. So if you can convert 1 to a fraction and 0.05 to a fraction, you can add the two fractions together. Your answer is

    asked by Tammy Evert on July 19, 2006
  8. math 116

    Is it always necessary to have a common denominator to add and subtract fractions? Why? What about multiplication and division with fractions?

    asked by Rosetta on March 24, 2008
  9. math

    i am having to add, subtract, multiplication and division on fractions. whloe numbers with fraction. My question is that i do not know how to do fractions at all and i need some help

    asked by marie on February 16, 2009
  10. math

    -8 2/3 - -5 1/3 How would you set up? Go here and scroll to 4 the answer would be -3 1/3

    asked by Jessica on November 13, 2006

More Similar Questions