Jalil and Victoria are each asked to solve the equation ax – c = bx + d for x. Jalil says it is not possible to isolate x because each x has a different unknown coefficient. Victoria believes there is a solution, and shows Jalil her work:

ax – c = bx + d
ax – bx = d + c
x (a – b) = d + c
x = x equals StartFraction d plus c Over a minus b EndFraction.
How can Victoria justify Step 3 of her work?