# Lesson 3 Count on or Count Back to Subtract

Let’s find the difference between numbers.

## Warm-up Number Talk: Tens and Hundreds

Find the value of each expression mentally.

## Activity 1 Jump Back, Back, Back

Jada and Andre found the value of

Here is their work.

Jada’s Work

Andre’s Work

What do you notice? What do you wonder?

Try Andre’s way to find the value of

. Show your thinking. Use a number line if it helps.

Find the value of

in your own way. Show your thinking. Use a number line if it helps.

## Activity 2 Who Spilled Paint?

Oh no! Diego spilled paint on his paper and now he can’t see all the numbers. Find the number hidden by the paint.

Find the number that makes each equation true.

## Practice Problem

## Problem 1

Find the value of each difference. Show your thinking. Use a number line or base-ten blocks if it helps.