Let's figure out what the formula should be first. I can't really read it the way it's typed.
Total number of bars = number of people(X) times bars per person (A)
Total number of bars = number of boxes (Z) times bars per box (Y)
Those are the same so

It looks like what was being asked was correct:

Solving for A, we multiply both sides by A and divide both sides by X, which really means move A to the numerator on the left, and X to the denominator on the right.
