For Enrique a 12 ounce bottle lasts for 16 weeks. This is a known fact. We need to find the amount of days or weeks an 18 ounce bottle of the same brand of shampoo last.
Now
12 ounce bottle lasts = 16 weeks
= (16 * 7) days
= 112 days
18 ounce bottle lasts = (112/12) * 18
= 168 days
= 168/7 weeks
= 24 weeks
So 18 ounce of the same brand of shampoo will last for 24 weeks.
