Răspuns:
Salutare!:)
(x+15)×10-100:5+90=100
(x+15)×10-20+90=100
(x+15)×10-20=100-90
(x+15)×10-20=10
(x+15)×10=10+20
(x+15)×10=30
(x+15)=30:10
x+15=3
x=3-15
x=-12
Succes!