A submarine kept a constant rate of ascent upon rising after a dive. After 5 minutes it was 360 feet below the surface of the water, and after 25 minutes it was 140 feet below. How long after starting its ascent was the submarine 250 feet below the surface?

Answer 1

In 20 minutes it rose 220ft
So, the depth is decreasing at a rate of 11 ft/min

360 = 415 - 11*5, so the depth

d(t) = 415 - 11t

So, when d=250,

415-11t = 250
11t = 165
t = 15

So, 15 minutes after starting, the depth was 250 ft.

Answer 2

The answer to this comment is known to be 60ft😉😃😍😜😘thanks for your time