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

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

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