Question

Simplify 7(B + 3) + 2B. 9B + 3 9B + 10 9B + 21

Answer 1

Expand

(7B + 21 + 2B)

Collect like terms

(7B + 2B) + 21

Simplify 

9B + 21

Answer: C) or the third option.

Answer 2

Remember, we can add like terms
also remember the commutative property of addition which is
you can move the order around when adding or a+b=b+a

also, distributive property which is a(b+c)=ab+ac

so

distribute first
7(B+3)=7(B)+7(3)=7B+21

now we have
7B+21+2B
by the commutative property
7B+2B+21
adding like terms
9B+21

answer is 9B+21