Since the sum of the angles of a triangle is 180 degrees, we simply have to add all the angles and equate it to 180 to solve for x. So:100 + 12x + 4 + 14x - 2 = 18026x = 78x = 3
So, x is equal to 3.
You could use a simple pencil test to figure it out.
Place a pencil vertically on the paper, and move it left to right or vise-versa
When moving it make sure the pencil doesn't hit two points at once if it does it is not a function, but this is not the case
This is a function