Answer:
x = 20°
Explanation:
You want to find x given the relationship between angles shown in the diagram.
Vertical angles
Vertical angles are congruent. That means their measures are equal:
5x +10° = 7x -30°
40° = 2x . . . . . . . . . add 30°-5x to both sides
20° = x . . . . . . . . . divide by 2
The value of x is 20°.
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Additional comment
The two angles are ...
5(20°) +10° = 110° = 7(20°) -30°