Answer: A
Step-by-step explanation:
6x + 12x + 90 = 180
18x + 90 = 180
-90 -90
18x =90
x= 5
6(5) + 12(5) + 90 = 180
30 + 60 + 80 = 180
180= 180 It makes sense that it is A because there is one right angle which has a measure of 90 degrees and the other one have two measures 6x and 12x and both of them have to also equal 90 degrees. So 90 pluse 6x plus 12x has to equal 180 because they all lie on a straight line and a straight line has an angle measure of 180 degrees.
