Answer:
Step-by-step explanation:
17) B. They are adding 2 to both sides.
18) A. A segment is equal to itself.
19) D. They are multiplying both sides by 2.
20) C. They are simply swapping the left and right hand sides of the equation
2n+7
=2(3)+7
=6+7
=13
OR
2(3)+7=13