Madyson borrows $1,200 from her father to purchase airplane tickets. The first week after borrowing the money, Madyson repays her father $50. Each week after that, she is able to repay her father $2 more than the previous week, except in the last week, when she finishes repaying the loan. How much is Madyson’s final payment?
Her final payment is 78$. Just do 50+52+54+56+58... and so on until you get up into the 1,100's. Then subtract that last number you got from 1200. The answer is 78.