Question

A boat travels 40 miles downstream (with the current) in the same time it takes the boat to travel 30 miles upstream (against the current). If the boat travels at 46 miles per hour, write an equation to solve for the speed of the current, x in miles per hour.

Answer 1

40/46+x=30/46-x

Explanation:

Speed=distance/time

s=d/t

x=speed of the boat

Downstream speed=x+46

Upstream speed=x-46

Downstream

s=d/t

x+46=40/t

t=40/(x+46)

Upstream

s=d/t

x-46=30/t

t=30/(x-46)

Equate upstream and downstream

30/x-46=40/x+46

30(x+46)=40(x-46)

30x+1380=40x-1840

30x+1380-40x+1840=0

-10x+3220=0

-10x=-3220

Divide both sides by -10

x=322

x=322 miles/hour