Two supplementary angles measure (3x + 5) and (9x - 5), the value of x is _____?

Two supplementary angles measure (3x + 5) and (9x - 5), the value of x is _____?

Explanation

Supplementary angles add up to 180°, so set up an equation:

(3x + 5) + (9x - 5) = 180°

Combine like terms:

12x = 180°

Divide both sides by 12:

x = 15°