9514 1404 393
Step-by-step explanation:
Finish the Given statement, make use of the relationships of angles and parallel lines, then finish the algebra.
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2. m∠6 = (1/8)m∠4 . . . . Given
3. m∠6 + m∠4 = 180° . . . . 3. same-side interior angles are supplementary
4. m∠6 + 8·m∠6 = 180° . . . . 4. Substitution (from 2, above: 8·m∠6 = m∠4)
Here is the "algebra" that gets you to line 5:
4a. 9m∠6 = 180° . . . collect terms
4b. m∠6 = 20° . . . . . divide by 9
4c. m∠4 = 8·20° = 160° . . . use the same relation as in step 4
5. m∠6 = 20°, m∠4 = 160° . . . . Algebra