Question

Your supposed to find the angle of the triangle but I know the answer 145 but I want to know how you get the answer

Answer 1

A straight line adds up to 180
So the line opposite of 137 should add up to 180
This gives us the equation 137+x=180 then x=43

The triangle also adds up to 180 degrees
So 102+43+x=180
The equation can be simplified to 145+x=180 therefore x=35


So x+?=180  because it is a straight line.
We can substitute x in making the equation 35+?=180
Now we want to solve for the ? so we'll subtract 35 from each side 
This leaves us with the equation ?=145

So we now know that the ?=145