Answer:
20°
Explanation:
ok so if 40 degrees is on one side its also on the side parallel from it
a straight line = 180 degrees
so 180 - 40 = 140
so 7x =140
we now divide 7 on both sides and get x=20 because the 7 cancels out
180 -40 =140
7x = 140
7x/7 =140/7
x=20
Hope I helped?