9514 1404 393
Answer:
25) 90°
26) 85°
27) 60°
28) 80°
Step-by-step explanation:
In problems 25, 26, 28, the marked angles are adjacent interior angles, so have a sum of 180°. In problem 27, the marked angles are corresponding angles, so are congruent.
25) The two angles are equal, so each is 180°/2 = 90°.
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26) (20x +5) +(24x -1) = 180
44x = 176 . . . subtract 4, simplify
x = 4 . . . . . . . divide by 44
20(4) +5 = 85
The bold angle is 85°.
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27) 6x = 5x +10
x = 10
6x = 60
The bold angle is 60°.
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28) (x+109) +(x+89) = 180
2x + 198 = 180 . . . . simplify
2x = -18 . . . . . . . . . . subtract 198
x = -9
x+89 = -9 +89 = 80
The bold angle is 80°.
