how to compare fractions

Question

Karina is baking bread. She buys a small bag of flour that contains 2 cups of flour. The recipe calls for 2 cups of flour. Does she have enough flour to bake the bread? Explain how she can compare the fractions to know for sure.

Answer 1

The easiest way to compare two fractions is to get the denominators to be equal and then see which numerator is larger and which is smaller. So for this problem you would multiply each fraction by 1 where 1 is shown as the denominator of the fraction being compared over itself (3/3 and 7/7)

(2/3)(7/7) and (5/7)(3/3) --> (then you multiply the top numbers across and the bottom numbers across-->

(2/3)(7/7)=(14/21) and (5/7)(3/3)=15/21, so now you can see that the bag of flour that Karina bought contains 2 and 14/21 cups of flour and the recipe calls for 2 and 15/21 cups of flour so she does not have enough flour since 15/21 is greater than 14/21. I hope that helps!