Question

A submarine descends into the ocean at a

Answer 1

18 mins.
Explanation:
Time taken to travel 20 m = 1 min
Time taken to travel 360m = x min
therefore:
1/20=x/360

(cross multiply)
20 x =360(isolate x by dividing both sides by 20)
x = 360
20 x
= 18 mins.