
Dad can't solve
The word problem (designated as algebra) reads:
In his fishing boat, Nathan went downstream moving at one hour less than he went upstream the same distance. If the current is moving at 4 miles per hour, how fast can he travel on still water, if it took him three hours to make the upstream trip.
I double checked the wording of the problem.

Ok I think this is how you solve it:
$\displaystyle x $ = speed he can row
$\displaystyle c $ = speed of current
$\displaystyle T_u $ = Time to travel Upstream
$\displaystyle T_d $ = Time to travel Downstream
$\displaystyle D $ = Distance traveled
$\displaystyle Distance = Speed * Time $
$\displaystyle Speed = x \pm c $
Since the Distance is the same in both directions we have:
$\displaystyle T_u(xc) = D = T_d(x+c) $
$\displaystyle T_u = 3 $
$\displaystyle T_d = 2 $
$\displaystyle 3(x4) = 2(x+4) $
$\displaystyle 3x12=2x+8 $
$\displaystyle x=20$
So his speed is 20 miles per hour