2x-4 & 5y
Because all sides are congruent, it is an equilateral triangle. You can see this based on the lines on the sides of the triangle. Because of this, all angles are equal to each other. In a triangle, the sum of angles is 180 degrees with each angle being equal to 60 degrees.
Because both angles are equal, you get. Since you're solving for x, set 5y equal to 60 then solve for x.
5y = 2x - 4
60 = 2x - 4
60 +4 = 2x
64 = 2x
32 = x
x = 32
To confirm if this is correct, plug in 32 for x in 2x -4
2(32)-4 = 64 -4 = 60 degrees
x = 32