David spent 5/12 of his money on some books and Mary spent 3/4 of her money on some files. After paying for their purchases, they had an equal amount of money left. If David had $52.50 left, what was the total amount of money David and Mary had at first?
(7/12)D = 52.5
D = 52.5(12/7) = 90.0
(1/4)M = 52.5
M = 210.0