Unit 2 Contents

4. Rosa started using this strategy to solve 24 − 9.
   
   1. What should she do to finish?
   2. Complete the number sentence that shows this strategy.
      24 − 10 + = 15

Use the Reasoning from Known Facts Workshop Menu in the Student Activity Book to choose practice problems. Choose problems from the first row of the menu.

Self-Check: Questions 5–6

When Mark uses a number line for subtraction problems, he often thinks of addition.

5. Mark solved 15 − 7 on the number line. Write a number sentence that shows Mark's strategy and his solution.
   
6. Solve 29 − 17 using Mark's strategy. Show or tell your strategy.
   

Use the Reasoning from Known Facts Workshop Menu in the Student Activity Book to choose practice problems. Choose problems from the second row of the menu.