Answer:
see explanation
Step-by-step explanation:
The 3 given angles in the triangle have a sum of 180°
Sum the 3 angles and equate to 180
3x + 3x + 8 +9x + 7 = 180 ← simplify left side
15x + 15 = 180 ( subtract 15 from both sides )
15x = 165 ( divide both sides by 15 )
x = 11
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3x + 8 = (3 × 11) + 8 = 33 + 8 = 41°
∠1 and 3x + 8 form a straight angle and are therefore supplementary, thus
∠1 = 180° - 41° = 139°
Which corresponds to the given angle of 139°
Hence m and n are parallel lines
