S=-1 see attachment for explanation
9 divided by 72 = 0.125
0.125 is the weight of one book
0.125 times 80 = 10kg.
So 80 books weight 10kg.
72 divided by 9 = 8 books make up 1 kg.
8 times 6 =48
Answer: Yes, It is 315, I'm 100% honest!
I think there is more to the question, but the equation to solve for the number of months until Rita has enough money to put a down payment for a condominium is 15,000=8,000+850X
