A boat travels with the current and can cover 100 miles in 4 hours. If the boat travels against the current, it can only travel 80 miles in the same time.

Question

How fast is the boat in still water, and how fast is the current?

Answer 1

The boat with current travels 100 miles in 4 hr, i.e. 25 mph and against the current 80 miles in the same 4 hrs, i.e. 20 mph.

This information can now be translated into algebra.

Let B = boat speed in still water and C = current speed.

B+C = 25

B-C = 20

Add the 2 equations to get the boat spped and use this value in either of the 2 equations to get the speed of the current.