a.(1.5^2+x)*0.2=10*0.1
(2.25+x)*0.2=1
2.25+x=1:0.2
2.25+x=5
x=5-2.25
x=2.75
b.(1.02^2-x)=0.1*2.2
1.0404-x=0.22
-x=0.22-1.0404
-x=-0.8204
x=0.8204
c.0.2*(0.2*(x-0.2)-0.2)=0.2+0.2
0.2*(0.2*(x-0.2)-0.2)=0.4
0.2*(x-0.2)-0.2=0.4:0.2
0.2*(x-0.2)-0.2=2
0.2*(x-0.2)=2+0.2
0.2*(x-0.2)=2.02
x-0.2=2.02:0.2
x-0.2=10.1
x=10.1+0.2
x=12.3