There are 52 weeks in the year, if she goes every two weeks 52/2 = 26
every time she goes she pays 1.50 for the shoes 1.50(26)= $39
If the shoes cost $48 to buy they are 48-39 = $9 more to buy than to rent.
So it would be less expensive to rent than to buy.
I hope this helps :) and good luck on your exam!