Answer:
24 units
Step-by-step explanation:
add (x+12) to itself 6 times and get 6x+72 after combining like terms, or multiply 6(x+12) and distribute to get the same thing 6x+72 and equal it to the perimeter.
6x+72 = 216 solve for x
6x = 144 divide
x = 24 units
