Answer:
25
Step-by-step explanation:
The angle markings indicate the angles are all congruent, making this an equilateral triangle. All sides are the same length, so you can use any pair of them for an equation:
... 2x +20 = 3x -5
... 25 = x . . . . . add 5-2x
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Check
Each side has length 70 = 2·25 +20 = 3·25 -5 = 4·25 -30.
