Question

Two angle measures in a scalene triangle are 77° and 62°. What is the measure of the third angle?

Answer 1

The total measure of the inner angles of a shape is determined by the expression;
(n-2)*180° where n is the number of sides.
(3-2)180°
1*180°
180° is the total measure of the inner angles.
To put that as an equation; 
180° = 77° + 62° + x°
x = 41°

Answer 2

Well we have the triangle.
We know that a triangle has a  total of 180 degrees, right?
So...
We add 77+62=139
180-139=
41 degrees.
Hope this helps!