A submarine left Hawai'i 2 hours before an aircraft carrier. The vessels traveled in opposite directions. The aircraft carrier traveled at 25 mph for 9 hours. After this time the vessels were 280 miles apart. Find the submarine's speed.

The speed of the submarine is 5 mph

Step-by-step explanation:

Let x represent the speed of the submarine.

A submarine left Hawai'i 2 hours before an aircraft carrier. If the aircraft carrier travelled for 9 hours and after this time, the vessels were 280 miles apart, it means that submarine travelled for 9 + 2 = 11 hours and the total distance covered by submarine and the aircraft is 280 miles.

Distance = speed * time

Distance covered by the submarine would be

11 * x = 11x

The aircraft carrier traveled at 25 mph. Distance covered by the aircraft would be

25 * 9 = 225

Therefore,

225 + 11x = 280

11x = 280 - 225 = 55

x = 55/11 = 5mph