A) The diagram is apparently supposed to be interpreted as showing the measures of two linear angles, that is, angles whose sum is 180°. The equation shows the sum of the angles is 180, so is ...
(x - 13) + (2x +1) = 180
B) Simplify the expression, add 12, and divide by 3 to find the value of x.
3x -12 = 180
3x = 192
x = 64
C) Fill in the value of x in the expressions for the angle measures.
∠ = 64 - 13 = 51
∠ = 2×64 +1 = 129
