Hi Jimi.

Ten percent of the sales is the profit, which becomes her earnings. So we can solve this with algebra.

Let S = the amount of sales she must have.
10% S = $50 000.

We want to find the value of S, so we need to make the left side of the equation just S (this is called isolating S). That means we have to get the 10% out of the left side of the equation. To do that, we will divide by 10% on both sides of the equation. Then the 10% cancels out on the left side:

10% S / 10% = $50 000 / 10%

therefore

S = $50 000 / 10%

Now remember that percent means per hundred, so 10% means 10 / 100, which is 0.10. So we can write it like this:

S = $50 000 / 0.10

Can you finish the question now?
Stephen La Rocque.