Marie, Brad, and Doug went to the mall. Brad spent three times as much money as Marie. Doug spent fifteen dollars more than Brad. If Doug spent $60 at the mall, which of the following equations should be used to find out how much money Marie spent?
3(m + 15) = 60 (where m represents the amount of money Marie spent)
3m + 15 = 60 (where m represents the amount of money Marie spent)
15m + 3 = 60 (where m represents the amount of money Marie spent)
3m – 15 = 60 (where m represents the amount of money Marie spent)

Question

Marie, Brad, and Doug went to the mall. Brad spent three times as much money as Marie. Doug spent fifteen dollars more than Brad. If Doug spent $60 at the mall, which of the following equations should be used to find out how much money Marie spent?
3(m + 15) = 60 (where m represents the amount of money Marie spent)		
3m + 15 = 60 (where m represents the amount of money Marie spent)
15m + 3 = 60 (where m represents the amount of money Marie spent)		
3m – 15 = 60 (where m represents the amount of money Marie spent)

anonymous · Answer

B = 3M
D = B + 15

If D spent 60, how much did M spent?

D = B + 15

Replace that B with the B from the first equation

D = 3M + 15

Since D spent 60,

60 = 3M + 15

Which is option B