Question

X =-12

Answer 1

Answer:

9 km/h   …. Current rate

12 km/h   ….. still water boat rate

Step-by-step 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