Equivalent Expressions: Simplifying 3(n+6)

B and D are equivalent to 3(n+6).

B can be simplified as follows:

3(n+6) = 3n + 18

D can be simplified using the distributive property:

2(n+6) + (n+6) = 2n + 12 + n + 6 = 3n + 18

Therefore, the correct options are B and D.