Answer:
105
Step-by-step explanation:
Theorem:
If parallel lines are cut by a transversal, then same-side interior angles are supplementary.
Lines AB and CD are parallel, and angles 3 and 6 are same-side interior angles, so by the theorem above, angles 3 and 6 are supplementary. That means that the sum of their measures is 180 deg.
m<3 + m<6 = 180
m<3 + 75 = 180
Subtract 75 from both sides.
m<3 = 105
Answer: 105 degrees
