# Lesson 13 Put It All Together: Add and Subtract Fractions

Let’s add and subtract fractions with unlike denominators.

## Warm-up Number Talk: Sums with \frac{1}{8}

Find the value of each expression mentally.

## Activity 1 Common Denominators

Tyler says: “To find the sum, I can use 18 as a common denominator.”

Han says: “To find the sum, I can use 24 as a common denominator.”

Clare says: “To find the sum, I can use 48 as a common denominator.”

Whom do you agree with? Explain or show your reasoning.

What is the value of

? Are there other common denominators you could use to find the sum? Explain or show your reasoning.

## Activity 2 Unlike Denominators

Find the value of each expression. Explain or show your reasoning.

## Practice Problem

## Problem 1

Find the value of each expression. Explain or show your reasoning.