Answer:
C (15c + 51)
Step-by-step explanation:
First off, you need to distribute the 3 to c and 10 resulting in the equation being 12c + 3c + 30 +21. After distributing, combine like terms, so 12c + 3c = 15c and 30+21 = 51, which results in the simiplified equation to be 15c + 51.
