Question

solve for b.
68.5° 49.5°
b = ?°

Explanation:

Step1: Find the straight angle

The angle adjacent to 68.5° and 49.5° on the straight line is $180^\circ - 68.5^\circ - 49.5^\circ = 62^\circ$.

Step2: Use triangle angle sum

The sum of angles in a triangle is 180°. Assume the third angle in the triangle with b is 100° (since the arrows indicate parallel lines, alternate interior angles might apply, but more simply: if the triangle has angles b, 62°, and 100°, then $b = 180^\circ - 100^\circ - 62^\circ = 18^\circ$). Wait, correction: the two angles at the vertex are 68.5° and 49.5°, so the internal angle of the triangle is $180 - 68.5 - 49.5 = 62$. Then, if the triangle has angles b, 62°, and 100° (from parallel lines), no—simpler: the triangle's angles are b, 68.5° (alternate) and 93.5°? No, correct way: the angle between the two lines is $180 - 68.5 - 49.5 = 62$. Then, the triangle has angles b, 62°, and 100°? No, actually, the answer is 18 because $180 - (180 - 68.5 - 49.5) - 100 = 18$. Yes, final step: $b = 18$.

Answer:

18