The partial circles in each corner mean that all 3 angles are identical, which means this is an equatorial triangle. In an equatorial triangle all three sides are the same.
We can set two of the equations to equal each other and solve for x:
3x -5 = 2x +20
Add 5 to each side:
3x = 2x +25
Subtract 2x from each side:
x = 25
