SOLUTION:
Exterior angle = Sum of opposite interiors angles
.
15x - 5 = 43 + (9x - 6)
15x - 5 = 43 + 9x - 6
15x - 9x = 43 - 6 + 5
6x = 42
x = 7
.
Answer: x = 7
The sum of the measures of the interior angles of a triangle is 180 degrees.
Make the three angles add up to 180 in an equation.
6x + 130 + 4x = 180
Combine like terms.
10x + 130 = 180
Subtract 130 from both sides.
10x = 50
Divide both sides by 10.
x = 5 is your answer.