Question

The equation d = 90 − 15t represents the depth d (in feet) of a scuba diver t minutes after beginning an ascent to the surface. How long does it take the scuba diver to reach the surface?

Answer 1

6 minutes

Explanation:

at the surface the depth d is 0 , then

0 = 90 - 15t ( subtract 90 from both sides )

- 90 = - 15t ( divide both sides by - 15 )

6 = t

that is it takes the diver 6 minutes to reach the surface