If you are selling parts and they cost you $12.00, how do you figure out what your markup and selling price are if your dollar markup is 40% of your selling price.

I came up with the equations

x=y-12 where x=markup y=selling price and 12=cost

from there i fiqured that x/y=40% so (y-12)/y=40% I don't know if this is correct or how to solve for y if it is.