Step by Step: If it takes 2 hours to design shorts to get $15 and 1 hours to make shirts for $8 you can multiply 8 by 2 and get 16 which is more than 15. The reason you multiply 8 by 2 is because it takes 2 hours to make 1 pair of shorts. With this you then multiply 16 by 9 which gives you 144.