-21=-7/8w

To solve for the variable, w, we need to isolate it on one side of the equation.

We can begin by multiplying both sides of the equation by -8 to get rid of the fraction:

-8*(-21) = -8*(-7/8w)
168 = 7w

Then, we can divide both sides by 7 to solve for w:

168/7 = 7w/7
24 = w

Therefore, the solution is w = 24.