x and w are parallel lines, so
• angles 2 and the one labeled 75º are congruent because they are alternating interior angles, and
• angles 1 and 2 are supplementary because they form a linear pair.
The first observation tells you that angle 2 has measure 75º, and angle 1 has measure m such that
m + 75º = 180º
so angle 1 has measure 180º - 75º = 105º.