Question

each side of equilateral triangle is 5 cm shorter than the side of square. the sum of the perimeters of the two figures is 251 cm. how long is each side of the triangle?
solution pls.

Answer 1

I will set up your definitions

let each side of the square be x
then each side of the triangle is x-5

"the sum of the perimeters of the two figures is 251 cm"
translate this into your equation, then solve for x
Replace you x value in the definitions.

let me know what you got

Answer 2

is the answer is x = 128

Answer 3

not very likely!

that would make the perimeter of the square alone equal to 512

wouldn't your equation have been
4x + 3(x-5) = 251 ??

I get x = 38
(which meets all the conditions)