Hi there!
Here are the steps into solving this equation :
4dy + 12 = 7dy
subtract 12 from each side of the equation
4dy = 7dy - 12
subtract 7dy from each side of the equation
-3dy = -12
divide each side of the equation by -3
dy = 4
divide each side of the equation by "d"
y = [tex]\frac{4}{d}[/tex]
There you go! I really hope this helped, if there's anything just let me know! :)