Odpowiedź:
A) x+2x=x+9
X+2x-x=9
2x=9/2
X=4.5
B)y+2y-5=11-y
Y+2y+y=11+5
4y=16/4
Y=4
C)3a+4=a-1+a+7
3a-a-a=-1+7-4
a=2
D)10-2b+6-b=10-b+4-b
-2b-b+b+b=10-10-6+4
-b=-2/*1
b=2
