Question 810814
to find the rate of the water you need to use the speed of the boat.
distance/rate
we are going to put downstream on one side and upstream on the other.
the distance for downstream is 22 miles.  the rate is going to be 18 + x. The reason for this is because when you are going down a river, the river pushes you along and increases your speed.  The overall speed is going to be more than 18.
{{{22/(18+x)}}}
The distance for going upstream is 14.  The rate is going to be 18 - x.  The river pushes against the boat causing the boat to slow down.  so the overall speed is going to be less than 18mph.
{{{14/(18-x)}}}
now make them equal to each other.
{{{22/(18+x)=14/(18-x)}}}
cross multiply and solve for x.
{{{22(18-x)=14(18+x)}}}
{{{396-22x=252+14x}}}
{{{144-22x=14x}}}
{{{144=36x}}}
{{{x=4}}}
the current of the water is 4mph.