Arrange these functions from least to the greatest value based on the average rate of change in the specified interval

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?

20 ! brainliest ! add and simplify your answer.

David and alton are training for a race. they spend 35 minutes stretching and then go on a 5 mile practice run. david runs at a pace of 7 min/mile. alton runs at a pace of 8 min/mile. write an equation for each runner that shows the total length of their workout. then solve each equation showing your work