Boat speed is equal in still water 20 kmch. Valery on a current floated 12 km and spent on it so much time how many went against the stream 8 km. Calculate watercourse speed.

299
S = v * t - a formula of a way-----------------------------------Let x (km/h) - watercourse speed, then 20 + x (km/h) - boat speed on a watercourse; 20 - x (km/h) - boat speed against the current the rivers. Equation: 12: (20 + x) = 8: (20 - x) - it is a proportion 8 * (20 + x) = 12 * (20 - x) - property of a proportion 160 + the 8th = 240 - the 12th the 8th + the 12th = 240 - 160 of the 20th = 80 x = 80: 20 x = 4 Answer: 4 km/h - watercourse speed .
315
Answer add