Question

A submarine left Pearl Harbor and traveled east. An aircraft carrier left four hours later traveling 30 mph in an effort to catch up to the submarine. After traveling 8 hours, the aircraft carrier finally caught up to the submarine. What was the submarine’s average speed?

Answer 1

Speed of sub ---- x mph

After 8 hours, at x mph, the sub went 8x miles
after 4 hours, at 30 mph, the carrier went 120 miles

8x = 120
x = .....

Answer 2

i got this thanks
distance of submarine = distance of aircraft
S.t = S.t
S(8+4) = 30.8
12S =240
S=2 mph

Answer 3

I actually messed up my times, should have been:

Speed of sub ---- x mph

time of travel of the sub is 12 hours
time of travel of the carrier is 8 hrs

After 12 hours, at x mph, the sub went 12x miles
after 8 hours, at 30 mph, the carrier went 240 miles

12x = 240
x = 20 mph

You clearly meant to say S = 20 , not S = 2
You also obviously caught my error.