the perimeter of the given equilateral tringle is 90 centimeters. Find x if its side length is (7x-5) centimeters

x = 5

Explanation:
Equilateral triangles have 3 sides of equal length.
therefore we start with 90 / 3 = 30
from here we can create the equation;
7x - 5 = 30
to solve this we start with + 5 to both sides, which gives us;
7x = 35
from here we divide both sides by 7 to isolate (x);
x = 5

Hope this helps :)