Lesson 14 Write and Solve Equations with Unknowns

    • Let’s work with equations with unknown numbers.

Warm-up Number Talk: Fives

Find the value of each expression mentally.

Activity 1 Card Sort: Unknown Numbers

Your teacher will give you a set of cards. Match each equation with a situation or diagram.

Activity 2 Write Equations with an Unknown Number

  • Write an equation to represent each diagram or situation. Use a symbol for the unknown. Be prepared to share your reasoning.

  • Find the number that makes each equation true. Rewrite the equation with the solution.

diagram or situation

equation with symbol

equation with solution

Diagram. 2 parts. 1 part labeled 5 and other part blank. Total length, 35.

Jada has some packs of sports cards. Each pack has 5 cards. If Jada has 45 cards, how many packs of cards does she have?

Diagram. A rectangle split into 5 parts, each labeled 2. Total length, question mark.
Diagram. 2 parts. 1 part labeled 5 and other part blank. Total length, 30.

The school has 6 bags. Each bag has 10 basketballs in it. How many basketballs does the school have?

Practice Problem

Problem 1

Write an equation for the situation. Use a ? for the unknown. Find the number that makes the equation true.

There are 4 soccer teams. Each soccer team has 10 players. How many players are there altogether?