Answer:
equation: 3x - 2 + 4x - 9 + 3x - 9 = 180
x = 20
Step-by-step explanation:
add all internal angles
∠H + ∠I + ∠J = 180
where:
∠H = 3x - 2
∠I = 4x - 9
∠J = 3x - 9
plugin the values into the ∠H + ∠I + ∠J = 180 formula:
equation: 3x - 2 + 4x - 9 + 3x - 9 = 180
combine similar terms: 3x + 3x + 4x = 180 + 2 + 9 + 9
simplify: 10x = 200
divide 10 both sides: x = 20
