# basic math

posted by
**chrissy**
.

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 fractions but I don't get it.

3 1/4 - 2 1/8 = 13/4 - 17/8 =

26/8 - 17/8 = 9/8 = 1 1/8

All you do is multiply the whole number by the denominator and then add the numerator: 3 x 4 + 1 = 13. Then put the 13 over 4, and you have changed the mixed number to a improper fraction that can be used in an addition or subtraction problem.

How will you convert the second mixed number in the problem? (Hint: 17/9 is not correct.)

Then, before you can subtract (or add) fractions, you have to convert them so they have common denominators. The obvious common denominator between ?/4 and ?/8 is 8, so that's not a problem; just convert the first fraction so the demoninator is 8.

http://www.themathpage.com/ARITH/fractions.htm

Let me know what you come up with.

=)

ok durr i think i just had a brain fart or something thanks.