Answer
$9t^{4} - 3t^{2} + 11t + 12 $
Work Step by Step
By simplifying the brackets we get
= $9t^{4} + 5t + 8 - 3t^{2} + 6t + 4$
Then we add like terms together which are terms that have the same variables.
= $9t^{4} - 3t^{2} + 6t + 5t + 4 + 8 $
= $9t^{4} - 3t^{2} + 11t + 12 $
