ok,so the equation is 2x +8=100 but their are 4 sides, so you will add 2x+2x and 8+8, so that will equal 4x +16=100. subtract 16 from 100 and it will give you 84.divide 84 by 4 and it will give you 21. to check your answer multiply 24 times add 16 and it gives you 100
