Answer:
6c² + 15c + 12
Step-by-step explanation:
Given
(3c² + 6c + 7) + (3c² + 9c + 5) ← remove the parenthesis
= 3c² + 6c + 7 + 3c² + 9c + 5 ← collect like terms
= 6c² + 15c + 12
