Answer:
4(a+b)
Step-by-step explanation:
OMG U GO TO MY SCHOOL!!!! What grade r u in?!?!
It might be a little late BUT the answer is B
Answer: 12-2r
Step-by-step explanation:
3r+12-5r
= -2r+12 or 12-2r

Hope you could get an idea from here.
Doubt clarification - use comment section.
You add all the sides together for perimeter