# Lesson 19 Solve Problems Involving Arrays

Let’s solve problems involving arrays.

## Warm-up Number Talk: One Less Group

Find the value of each expression mentally.

## Activity 1 Array of Colors

There are 7 rows. Each row has 5 crayons. How many crayons are there?

Solve this problem. Explain or show your reasoning.

Represent the situation with an array and an equation with a symbol for the unknown.

## Activity 2 Tyler’s Trees

For each problem:

Write an equation with a symbol for the unknown to represent the situation.

Solve the problem. Show your reasoning.

A field of coconut trees in Mexico has 5 rows of trees. Each row has 9 trees. How many trees are there?

After learning about growing coconuts in Mexico, Tyler wants to plant coconut trees in his backyard in Florida. His mom will only let him plant 2 rows of 4 trees in his backyard.

How many trees will Tyler plant?

## Practice Problem

## Problem 1

There are 5 rows of chairs in the room. There are 4 chairs in each row. How many chairs are in the room?

Write a multiplication equation to represent the situation.

Find the value that makes your equation true.