Answer
$-16y^3 - 54y^2 +y - 12$
Work Step by Step
We simplify by removing the parentheses and then add the like terms as follows:
$$
(-16y^3 - 42y^2 - 3y - 5) - (12y^2 - 4y + 7)\\
=-16y^3 - 42y^2 - 3y - 5- 12y^2 + 4y - 7\\
=-16y^3 - 54y^2 +y - 12
.$$
