Answer:
14[tex]s^{4}[/tex] - 7s² + 15
Step-by-step explanation:
Remove the parenthesis on the first 2 and distribute the third by - 1
= 12[tex]s^{4}[/tex] - 6s² + 4s + 6[tex]s^{4}[/tex] - 4s + 27 - 4[tex]s^{4}[/tex] - s² - 12 ← collect like terms
= 14[tex]s^{4}[/tex] - 7s² + 15
