It takes a ship 3 hours to cover 72 km with the current and 4 hours against the current. Find the speed of the ship in still water and the speed of the current.

X - speed of the ship in still water

a - speed of current

(x+a) - speed with current

(x-a) - speed against current

(x+a) * 3=72

(x-a) * 4=72

x+a=24

+ x-a=18

2x = 42

x = 21

x+a=24, 21+a=24, a=3

The speed of the ship in still water = 21 km/h,

the speed of the current = 3 km/h.