Hey there!
The correct answer is the last option, 140.
The shape shown is a triangle, and a triangle has a total measure of 180° . . .
If we add 30 and 10 then subtract that from 180, you will get your answer.
30 + 10 = 40
180 - 40 = 140
Answer: 140 ←
Hope this helps you,
Have a wonderful day! :)