I need help with my math homework

Question

A 12oz bottle of shampoo last Enrique 16 weeks. How long would you expect an 18oz bottle of the same brand to last him?

Answer 1

Assuming Enrique uses the shampoo at the same rate, it should last 18/12 times as long.  

 

(18/12)(16 weeks) = ? weeks

Answer 2

12/16 = 18/w

 

Cross multiply.

 

12w = 288

w = 24