Question

what is the measure of angle 4 if angle 5 = (2x) and angle 4 = (x+9)?

Answer 1

m∠4 = 66° (option C)

Explanation:

m∠4 = (x + 9)°

m∠2 = (2x)°

m∠4 + m∠2 = 180° (sum of angles on a line)

(x + 9)° + (2x)° = 180°

Expand the bracket:

x + 9 + 2x = 180

collect like terms and subtract 9:

x + 2x + 9-9 = 180 - 9

3x = 171

divide both sides by 3:

3x/3 = 171/3

x = 57

m∠4 = (x + 9)°

m∠4 = 57 + 9 =

m∠4 = 66° (option C)