1.Spunem ca numarul=a
(a+25)*3-100=17
(a+25)*3=100+17=117
a+25=117:3=39
a=39-25
a=14
2.Spunem ca numarul=x
(x+19)*3+11=103*2=206
(x+19)*3=206-11=195
x+19=195:3=65
x=65-19=46
3.Spunem ca nr este x
(440:4)-100+x:3=21
110-100+x=63
10+x=63
x=63-10
x=53
P.S-- * inseamna inmultit