A + B = 65...Equation 1
B + C = 140...Equation 2
Solve Equation B for C.
C = 140 - B
The sum of the angles in a triangle is 180 degrees.
We know that A + B = 65.
65 + C = 180
We know that C = 140 - B.
65 + 140 - B = 180
205 - B = 180
-B = 180 - 205
-B = -25
B = -25/-1
B = 25
Plug B = 25 into B + C = 140 to find angle C.
25 + C = 140
C = 140 - 25
C = 115
Angle B = 25°.
Angle C = 115°.
Understand?
