y^2=-x and 3y-x=4

I am setting up the double integral as dxdy,

for the dx limit I have 3y-4 on bottom and -y^2 and top, and I understand that. However, I see the solution guide for dy limit has -4 to 1, and I am not understanding how they get that?

solution: Calculus (9780470647721), Pg. 1016, Ex. 30 :: Homework Help and Answers :: Slader