Let the x be the amount of money Maria had.
3/7 + 1/4 + 1/8 = 45/56
She spend 45/56 of x.
∴ 45/56 × x = (45/56)x
1 - 45/56 = 11/56
(11/56)x is the money that was left.
This is equivalent to 11.
(11/56)x = 11
11x = 11×56
11x = 616
x = 616/11
= 56.
Maria had #56.
