Răspuns:
suma initiala=150 lei
Explicație pas cu pas:
a=suma de bani
0,4=4/10
I. 4/10 x a=> 4a/10
II.1/3 x (a-4a/10)
III. 60 lei
4a/10+(1/3 x (a-4a/10))+60=a
4a/10+6a/10x1/3+60=a
2a/5+a/5+60=a
3a/5+60=5a/5
60=5a/5-3a/5
60=2a/5
2a=60 x 5
2a=300
a=150 lei