okay wait before i answer, is this for your points on a graph?
u = -(6/7)w
place all values with 'u' on one side of the equation.
4u + 8w = - 3u + 2w
4u + 3u = 2w - 8w
further simplify the equation by solving the addition and subtraction.
7u = - 6w
make 'u' the independent variable by placing its co-efficient on the right-hand side.
u = - (6/7)w
15.36 per mile
but forgot to round
i am pretty sure