Answer:
The classmate's only error is that the slope of the parallel line should be 3 aswell.
Step-by-step explanation:
Parallel lines always have the same slope to each other
To form a linear pair means that when added, they equal 180 degrees.
but if they have equal measures....180/2 = 90...then they would both equal 90 degrees.....and 90 degrees is a right angle.
So ABC and CBD are both right angles
