Respuesta :

make y the subject 
x-12=4y then divide all sides by 4
x\4-3=y
First off, you need to leave the y by itself.
x=12+4y (put the twelve one the other side, by subtracting it)
x-12=4y (divide by 4)
1/4x-3=y -> y=1/4x-3 done!