A runner ran 2/3 of a race in 21 minutes. They ran the entire race at a constant speed How long did it take to run the entire race?

31.5 minutes

Step-by-step explanation:

21 / 2 = 10.5

10.5 x 3 = 31.5

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

eventually after a few more steps, your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x