Answer:
3x(2+n)+[7+n]
Step-by-step explanation:
The answer is kind of self-explanatory, but think of it this way. If n=5, then the equation would be 3x(2+5)+[7+5]. First we would solve 2+5 which is 7. Then we would do 7+5 which is 12. We are now left with 3x7+5.
