Answer: C) 25
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Work Shown:
5x+4 = 8x-71 ..... vertical angles are congruent
5x+4+71 = 8x-71+71 ... add 71 to both sides
5x+75 = 8x
5x+75-5x = 8x-5x ... subtract 5x from both sides
75 = 3x
3x = 75
3x/3 = 75/3 .... divide both sides by 3
x = 25
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As extra info, you can plug this x value into either expression like so
5x+4 = 5(25)+4 = 125+4 = 129
or
8x-71 = 8(25)-71 = 200-71 = 129
Getting the same result (129) each time helps confirm we got the right x value.
