Answer:
x = 14
Explanation:
If the perimeter is 80, then that is (x+6) + (x+6) + (x+6) + (x+6). If you want to find x, you have to get rid of 6. 6+6+6+6 = 24. The perimeter, 80, minus 56. You then divide 56 by 4 to get x. That is 14. To check, you find (14+6)*4. That is 80.