Answer:
132
Step-by-step explanation:
That is an 180 degree angle so just do:
180-42=a
a=132
138 degrees.
A straight line is equal to 180 degrees. 42 is some, so you would subtract 180 and 42. That is 138 degrees. (When two or more angles add up to 180 it's called supplementary angle) Hope this helps
