I don't get Benchmark question #4

Adriver from the university of florida women’s swimming and diving team is competing in the in ncaa zone b championships

Solve for n? [tex]z = \frac{3}{4} mn[/tex]

Boris needs to buy plastic spoons. brand a has a box 42 spoons for $2.37. brand b has a box of 72 spoons for $3.57. find the unit price for each brand. then state which brand is the better buy based on the unit price. round your answer to the nearest cent.