Question

The total number of degrees, D, in an n-sided polygon is given by the formula D=180(n-2). When Janelle solves for n, she gets n=D+360/180. Sophie solved the same equation for n and got an equivalent equation. Which of the following could be Sophie’s equation?

n=D/180 +2


n=D/180 -2


n=D-178


n=D-182

Answer 1

D=180(n-2)
Solving for n. Dividing both sides of the equation by 180:
D/180=180(n-2)/180
D/180=n-2
Adding 2 both sides of the equation:
D/180+2=n-2+2
D/180+2=n
n=D/180+2

Answer: First Option n=D/180+2