remember, you can do anything to an equation as long as yo do it to both sides
minus 11 bothsides
a-11=4b-4c
minus 4b both sides
a-11-4b=-4c
divide both sides by 4
[tex]\frac{a-11-4b}{4}=-c[/tex]
multiply both sides by -1
[tex]\frac{-a+11+4b}{4}=c[/tex]
[tex]c=\frac{-a+11+4b}{4}[/tex]
[tex]c=\frac{4b-1+11}{4}[/tex]