Maggie is as old as she was a bit ago: 9 years old.
If 4 is added to the sum, it is 4 times Maggie's age. Thus, her age is 36/4 = 9.
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(maggie's age) + (3×(maggie's age) -4) = 32
4×(maggie's age) = 36 . . . . . . . . . . simplify, add 4
(maggie's age) = 36/4 = 9