One person can do a certain job in twentyone minutes and another person can do the same job in
twenty eight minutes. How many minutes will it take them to do the job together?

24.5

Step-by-step explanation:

Divide each of their jobs in half and then add the halves together so that would be 10 1/2 and 14 and then equals 24 1/2

1,918

step-by-step explanation:

x is the total time in minutes for the free response

you are given number of questions as 15 - m and time per item as 8 minutes

to find x multiply the two givens together:

x = 8 * (15-m) = 8(15-m)