An equilateral triangle has all 3 sides the same length.
Set two of the sides to equal each other and solve for X, then you can calculate the length of the sides.
12x - 22 = 10x - 6
Add 22 to both sides:
12x = 10x + 16
Subtract 10x from both sides:
2x = 16
Divide both sides by 2:
x = 8
Now you know x, solve for the side length:
12x - 22 = 12(8) - 22 = 96-22 = 74
10x-6 - 10(8) - 6 = 80 -6 = 74
7x +18 = 7(8) +18 = 56+18 = 74
Each side is 74 units.