Chapter 8.CR, Problem 14CR

a. Think of a number.

Add $17$.

Double the result.

Subtract $4$.

Double the result.

Add $20$.

Divide by $4$.

Subtract $20$.

Your answer will be your original number. Explain how this “trick” works.

b. Fill in two more steps that will take you back to your original number.

Think of a number.

Add $18$.

Multiply by $4$.

Subtract $7$.

.

.

.