Explanation:
Note that the angle with the measurement (8x + 10) & (10x - 10) are corresponding, which means that the would have the same measurements. Set the two equal to each other, and solve for x.
(8x + 10) = (10x - 10)
Isolate the variable (x). Subtract 10 & 10x from both sides.
8x (-10x) + 10 (-10) = 10x (-10x) - 10 (-10)
8x - 10x = -10 - 10
Simplify.
-2x = -20
Isolate the variable (x). Divide -2 from both sides.
(-2x)/-2 = (-20)/-2
x = -20/-2
x = 10
10 is your measurements for variable x.
Plug in 10 for x in both of the expressions:
10x - 10 = 10(10) - 10 = 100 - 10 = 90
8x + 10 = 8(10) + 10 = 80 + 10 = 90
Both measurements = 90°
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