Question

A boat traveled 280 miles downstream and back. The trip downstream took 7 hours. The trip back took 14 hours. Find the speed of the boat in still water and the speed of the current.

Answer 1

Let, the speed of boat = x 
Speed of current = y
So, x + y = 280/7
x + y = 40   ---- first equation

x - y = 280/14 
x - y = 20  
x = 20 + y

Substitute this value of x in first equation, 
20 + y + y = 40
2y = 40 - 20
y = 20/2
y = 10

Substitute this in first equation, 
x + 10 = 40
x = 30

In short, Speed of Boat = 30 mph, & speed of current = 10 mph

Hope this helps!