Answer:
C
Explanation:
∠ 7 and ∠ 2 are alternate angles and are congruent (equal ) , then
∠ 7 = ∠ 2 ( substitute values )
10x - 30 = 5x + 5 ( subtract 5x from both sides )
5x - 30 = 5 ( add 30 to both sides )
5x = 35 ( divide both sides by 5 )
x = 7
Then
∠ 7 = 10x - 30 = 10(7) - 30 = 70 - 30 = 40°
∠ 5 and ∠ 7 are a linear pair and sum to 180° , that is
∠ 5 + ∠ 7 = 180°
∠ 5 + 40° = 180° ( subtract 40° from both sides )
∠ 5 = 140°