Answer:
x=20
Step-by-step explanation:
the sum of the angles of a triangle is 180
so it means,
100+40+(2×)=180
140+(2×)=180
2×=180-140
2×=40
divide both sides by 2
x=20
to prove this substitute 20 inside see if the result is 180
40+100+(2×)=180
×=20
40+100+(2 (20))=180
140+40=180
140+40=180
Good luck.
