Determinați a e R...

A 5(x+2)-2(1-x)=x+20
5x+10-2+2x=x+20
6x=12
x=2
B .(a+2)x-a=1
(a+2)2-a=1
2a+2-a=1
a=1-2=-1
Răspuns:
a=-1