Question

X =-12

3. A boat traveled 210 miles each way downstream and back. The trip downstream took 10 hours. The trip back took 70
hours. What is the speed of the boat in still water? What is the speed of the current?

Answer 1

9 km/h …. Current rate

12 km/h ….. still water boat rate

Explanation:

The speed of the boat supposed to be x km/h

The current rate is y km/h

(x + Y) * 10 = 210

(x – y) * 70 = 210

x + y = 21 ….. ①

x –y = 3 ….. ②

①’- ②’ … 2y = 18

Y = 9 km/h …. Current rate

X = 9 + 3= 12 km/h ….. still water boat rate