11) x = 5°
working:
6x = 30°
x = 30° / 6
x = 5°
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12) x = 29°
working:
(4 + 5x) + (x + 2) = 180°
4° + 5x + x + 2° = 180°
6x + 6° = 180°
6x = 174°
x = 174° / 6
x = 29°
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13) x = 21°
working:
(3x + 12) + 5x = 180°
3x + 12 + 5x = 180°
8x = 180° - 12°
x = 168° / 8
x = 21°
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14) what you wrote is correct
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15) x = 29°
working:
(2x + 1) + (x + 2) = 90°
2x + 1° + x + 2° = 90°
3x + 3° = 90°
3x = 87°
x = 87° / 3
x = 29°
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16) x = 17°
working:
(4 + 2x) + (3x + 1) = 90°
4 + 2x + 3x + 1 = 90°
5x + 5 = 90°
5x = 85°
x = 17°
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