How to find the perimeter of a square one side is 10x other side is 6x+8?

To find the perimeter of the square, you add all four sides together:
10x + 10x + (6x + 8) + (6x + 8)
20x + 12x + 16 = P
32x + 16 = P

you have to find x to get the actual perimeter. Since the shape is a square, all 4 sides are equal, so you can set 10x and (6x + 8) as equal to each other.
10x = 6x + 8
4x = 8
x = 2

Now you just plug in x and finish the rest of the problem, and you have the
32(2) + 16 = P
64 + 16 = P
P = 80

(if you find this helpful, marking this as the brainliest answer would make my day :)