Answer:
900 min = 15 hours
Explanation:
when we convert the velocities of the ships into miles/ min we get
45mph = 45m/60min = 0.75m/min
36mph = 36m/60min = 0.6m/min
The equations determining the distances of the ships from the port M (set at x=0) are
D1 = 0.75t (for 45mph ship)
D2 = 162 + 0.6(t-45) (for 36mph ship)
The solution to these equation lie at t= 900 minutes; therefore the two ships will meet 900 minutes after the departure of the first ship.