.9x-2.1+.9=.2(5-x) multiply .2(5-x)
.9x-2.1+.9=1-.2x; add - 2.1 + .9
.9x-1.2=1-.2x; cancel -2x by adding it by itself and add it on the .9x
1.1x-1.2=1; cancel -1.2 by adding it by itself and add it on the 1
1.1x=2.2; divide 1.1 so it can be canceled and then on 2.2
x=2 :)