LESSON 7 Workshop: Reasoning from Known Facts

Use the following Self-Check questions to check your progress with using strategies to subtract.

Self-Check: Questions 1–4

When Rosa uses a number line for subtraction problems, she often thinks of tens.

1. Here is her solution for solving 14 − 10.
   
1. How did she know to stop at 4?
2. Complete the following number sentence: 14 − = 4
2. Here is Rosa's solution for solving 14 − 9.
   
1. Explain Rosa's steps. What is the answer?
2. Complete the following number sentence that shows Rosa's strategy.
   14 − 9 = 14 − 10 +
1. Use Rosa's strategy to solve 14 − 8. Explain your steps.
2. Complete the number sentence that shows this strategy.
   14 − 8 = 14 − 10 +