posted by .

adding and subtracting mixed numbers in lowest terms; 5 1/2 - 2 4/5, I got as far as 3 46/10 but don't know how to break it down into lowest term.

• math 4th grade -

Here is how I would do this:

5 1/2 - 2 4/5
= 11/2 - 14/5 , (mixed numbers are useless in calculations)
= 55/10 - 28/10
= 27/10 or 2 7/10

I have no idea how you can come up with 3 46/10 ??

• math 4th grade -

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.

Similar Questions

1. algebraic fractions in lowest terms

40c to the 5th power over 10c to the 4th power in lowest terms?
2. 4th Grade Math

Re: Factor Numbers My son has to write at least two ways to break down numbers - I know he did not learn this in school but I would like to help him at home, please help me I have not done this work in over 30 years. He has to break …
3. 4th Grade Math

Re: Factor Numbers My son has to write at least two ways to break down numbers - I know he did not learn this in school but I would like to help him at home, please help me I have not done this work in over 30 years. He has to break …
4. math

what is 320/380 (or in fraction term) in lowest terms?

Please finish these questions so I can check my answers. All my answers are at the bottom. Adding and subtracting mixed numbers. Please finish these questions. The answer must be reduced to lowest terms! 1. 3 2/5 + 6 1/5= 2. 4 2/5 …
6. Math

I am having trouble understanding how to reduce fractions to its lowest term... All I can understand is I have to find the lowest number that will divide into both numerator and denominator. How do I understand the solution on how …
7. math HELP

How would I change the improper fraction 56/15 to mixed number in lowest terms?
8. math

add mixed numbers in lowest terms 3 3/5 + 1 1/2= what in lowest terms
9. School

I was just wondering... So like, my teacher drops the lowest grade every new term and when my teacher dropped my lowest grade which says "no count" next to it, my grade went down. Is this possible?
10. 4th grade math

Find the value of each expression in lowest terms 3/4 + 1/16=

More Similar Questions