The speed of a motor boat in still water is 15 km / h and the speed of the current is 3 km / h how long will the boat spend

The speed of a motor boat in still water is 15 km / h and the speed of the current is 3 km / h how long will the boat spend on moving from one pier to another and vice versa if the distance between them is 36 km

1) 15 + 3 = 18 kilometers per hour – the speed of the boat downstream
2) 15-3 = 12 kilometers per hour – the speed of the boat against the stream
3) 36: 18 = 2 hours the boat will spend on the way there
4) 36: 12 = 3 hours the boat will spend on the way back
5) 2 + 3 = 5 hours the boat will spend on the way back and forth
Answer: 5 hours