jmc

First we get all the terms with $y$ on one side by subtracting $1.7y$ from both sides. This gives us $4+0.6y=-20$. Subtracting 4 from both sides gives $0.6y=-24$. Dividing both sides by 0.6 isolates $y$ and gives us $y=-24/(0.6)=-240/6=\boxed{-40}$.