Answer:
90°
Step-by-step explanation:
Ok, I get it now.
Draw two perpendicular lines. Starting at any of the right angles, name them 1, 3, 2, 4 going around in order.
Now you have vertical angles 1 and 2, vertical angles 3 and 4, and angle 3 is adjacent to angles 1 and 2. this is exactly what the description states.
Since angles 3 and 4 are right angles, then all angles are right angles.
m<1 = m<2 = m<3 = m<4 = 90
m<4 + m<1 - m<2 = 90 + 90 - 90 = 90
Answer: 90°
