Answer:
x = -6.
Explanation:
First thing to notice is that this is the third angle in a triangle, and all 3 angles have to equal 180.
Subtract 75 and 40 from 180 to get the missing angles value.
180 - 75 - 40 = 65
So now we know the missing angle has to be 65, or can be written as:
x + 71 = 65.
To solve this, just subtract 71 from both sides.
x = -6.