Add up the lengths of the several sides of the polygon.
Examples: The perimeter of a triangle is the sum of the lengths of the 3 sides.
The perimeter of a hexagon is the sum of the lengths of the 6 sides.
And so on.
I highly recommend drawing any polygon whose perimeter you wish to calculate.
Step-by-step explanation:
first way by sitting 3 person in one chair

The difference is the result of a subtraction problem.
We are given two values that are being subtracted: 54 and a number, represented by 
So, represent this mathematically with
.
-24 would be on the far right and then -4 would be closer to zero