Fraction Addition/Subtraction - Common Denominators

K Redmond

Adding/Subtracting Fractions with Common Denominators

Suppose Josh ordered a pizza and sat down to watch football. The pizza was cut into 6 equal slices. During the first half of the game, he ate one slice and during the second half, he ate another. How much of the pizza did Josh eat?
Josh ate 2 out of 6 slices. 2 out of 6 is written as the fraction . However, when solving problems, it's always good to look at how to solve them in multiple ways. Each piece of the pizza can be thought of as a unit fraction of . Since Josh ate two slices, we can think of these are two separate unit fractions of . When we add them together, we see . However, we always want to think of our answers in reduced fraction form, so we reduce and find . This is illustrated for you in your workbook. When adding fractions with common denominators, we can add together the two numerators while leaving the denominators the same. The same is true for subtraction - to find the difference between two fractions with common denominators, subtract the numerators and leave the denominator the same (ex. ).

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