I think you meant to put 3x +7. anyhow, i'll use numbers 1, 2, and 3. that would be 10, 13, and 16.
It’s 360 degrees. The measure of one exterior angle is equal to 360 divided by the number of sides in the polygon
Answer:
4 + 4 = 8
8+4 = 12
12+4 = 16
16+4 = 20 this is your answer
Step-by-step explanation: