Answer
$-0.8y^{2}+0.6y-0.6$
Work Step by Step
$(-0.3y^{2}+0.6y-0.3)-(0.5y^{2}+0.3)$
Remove both parentheses. To remove the second one, change the sign of every term inside it:
$-0.3y^{2}+0.6y-0.3-0.5y^{2}-0.3=...$
Simplify by combining like terms:
$...=-(0.3+0.5)y^{2}+0.6y-(0.3+0.3)=-0.8y^{2}+0.6y-0.6$
