Question

In the figure below, if line r is parallel to line s, m angle A=3x+5 and m angle B = 5x - 9 , what is m angle B ?

Answer 1

∠B = 26°

Explanation:

Parallel lines and transversal:

r // s

When parallel lines are cut by a transversal, the alternate exterior angles are congruent.

∠B = ∠A

5x - 9 = 3x + 5

Add 9 to both sides

5x = 3x + 5 + 9

5x = 3x + 14

Subtract 3x from both sides,

5x - 3x = 14

2x = 14

Divide both sides by 2

x = 14/2

x = 7

∠B = 5x - 9

= 5*7 - 9

= 35 - 9

∠B = 26°