Math Help - Solve by substitution method

I have a system of equations that illustrates two different floor plans (60 total) for sale, four times more of the second are available than the first (x= the first floor plan, y=the second:
x+y=60
y=x(4)

I need help solving how many of each are available via substitution. I assumed that I could substitute y for x (y+1)in the first equation but that is not checking. I appreciate help with this!

x + y =60
y = 4x

substite "y=4x" in the first equation
x + 4x = 60
5x=60
x=12