A rectangular lot has a river on one side and is fenced off into 3 areas with 752m of fencing. Find the dimensions and its maximum area. Note: There is no fencing along the river

I have:

Perimeter = 752m

$\displaystyle 3w + 2l = 752$

$\displaystyle 2l = 752 - 3w$

$\displaystyle

l = 376 - 3/2w

$

Area = l x w

$\displaystyle A = (376-3/2w)(w)$

$\displaystyle A = [376w-(3/2w^2)]$

Thats what i have so far, don't know if its right or wrong. Would be gratefull if anyone could tell me if what i have so far looks right, and what/how to do next.