x-suma initiala
1/4 din x= 1/4 * x= x/4 - prima data
x-x/4= (4x-x)/4= 3x/4 -restul
1/6 din 3x/4= 1/6 *3x/4= x/8 -a doua oara
3x/4- x/8= (6x-x)/8= 5x/8 -noul rest
1/3 din 5x/8 +120= 1/3 * 5x/8= 5x/24 +120 -a treia oara
5x/8 -(5x/24 +120)= (15x-5x+960)/8= (10x+960)/8 -noul nou rest
(10x+960)/8= 600
10x+960= 8*600
10x+960=4800
10x=4800-960
10x=3840
x=384 lei