Bob has 3/4 as much money as Dan. Dan received another $15. As a result, Bob had 6/11 as much money as Dan. How much did Dan have at first?
+128408 B = (3/4)D
After Dan received $15 he has D + 15
So
B / ( D + 15) = 6/11
(3/4)D / ( D + 15) = 6 /11 cross-multiply
11 * ( 3/4)D = 6 (D + 15)
(33/4)D = 6D + 90
(33/4)D - 6D = 90
(33/4)D - (24/4)D = 90
(9/4)D = 90
D = (4/9) (90) = $40 = what Dan started with
+36915 B = 3/4 D
Then add 15 to D
B = 6/11(D+15) Sub in the red equation
3/4D = 6/11D + 90/11
(33-24)/44 D = 90/11
D = 44/9 * 90/11 = 40 Dollars (as CHris already showed !)
