Need for hw i have no idea how to solve it

Consider what is done to u.

When you solve for u, you "undo" these operations in reverse order.

Division by 2 is undone by multiplying by 2. You do this to both sides of the equation.

... 2×F = 2×(u-w)/2

... 2F = u - w . . . . . . . simplified

Now, w is subtracted. You undo that by adding w to both sides of the equation.

... 2F + w = u - w + w

... 2F + w = u . . . . . . .simplified

If you like, you can swap sides so that u is on the left side of the equal sign.

... u = 2F - w

1/8 is left? add a bit more info plz