Item 4 The sum of the angle measures of the polygon is 540°. Write and solve an equation to find the value of x. An equation is =540. The solution is x= .
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Let's set the sum of the angle measures equal to 540 degrees.
139 + 3x + 5x - 10 + 10x - 9 + 3x = 540
Let's combine like terms.
21x + 120 = 540
Subtract 120 from both sides.
21x = 420
Divide both sides by 21
x = 20