Answer:
2. Since it is equilateral, we just set up an equation with using any two sides (since they are all equal)
12x - 22 = 10x - 6
12x - 10x - 22 = -6
2x - 22 = -6
2x = 22 - 6
2x = 16
x = 16/2
x = 8
Each side = 74
3. Same formula for this. Get any two sides and setup the equation.
4x - 25 = x + 14
4x - x - 25 = 14
3x = 25 + 14
3x = 39
x = 39/3
x = 13
Each side = 27
4. This one is also simple. Since DE = EF. We substitute its sides with the equations.
8x - 13 = 5x + 17
8x - 5x - 13 = 17
3x - 13 = 17
3x = 17 + 13
3x = 30
x = 30/3
x = 10
DE and EF = 67
DF = 31