Answer: Part A = Age, Part B = 154 - 0.7a, Part C = 140 beats per minute (BPM)
Step-by-step explanation: The question states "...in beats per minute, depends on a person's age and can be represented..." and the variable is a, so a is age. To rewrite an expression, you need to multiply the number outside the parentheses with the terms inside the parentheses. In this case 0.7 * 220, which is 154 and 0.7 * a which is 0.7a. So the expression rewritten is 154- 0.7a. In order to solve question C you need to plug in the variable. So 0.7(220 - 20) or 154 - 0.7 * 20, whichever is easier. After solving, your answer will be 140 beats per minute.
