a). 7*8=56, deci fiecare paranteza poate fi egala cu 7 sau 8.
x+1=7, x=6
x+2=8, x=6
incers, x+1=8, x=7
x+2=7, x=5
este fals
b). (x+15+30):6=6
x+15+30=6*6=36
x+15=36-30=6
x=6-15=-9
c).2•(x+2)•5+3•(x+2)=273/7=39
10(x+2)+3(x+2)=39
13(x+2)=39
x+2=39/13=3
x=3-2=1
