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
![AX=YZ](https://img.qammunity.org/2019/formulas/mathematics/high-school/5y47yeogry1ye8fe5wffjvzor9zsa4nzp5.png)
It looks like what was being asked was correct:
![X=(YZ)/(A)](https://img.qammunity.org/2019/formulas/mathematics/high-school/93oxdj9q23ewabcjhwnw03vijkq1ibyre6.png)
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.
![A=(YZ)/(X)](https://img.qammunity.org/2019/formulas/mathematics/high-school/7v9u9huzg4hdhavc3kwozk8gh8ix0p1sfv.png)