Question

the sum of the measures of two exterior angles of a triangle is 255. What is the measures of the third exterior angle?

Answer 1

there is a property for any polygon that you need

the exterior angles of any polygon sum to 360 degrees

you know the sum of 2 of the angles use this and the property to find the 3rd

Answer 2

So would the answer then be 105,
if you take 255 away from 360?

Answer 3

that's correct