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)
D = 180n -360
180n = D +360
n = (D / 180) + 2

So, the answer is "A"
And we can test this with a square, sum of angles = 360
n = (D / 180) +2
n = (360 / 180) +2
number of sides = 4
correct

Source:
http://www.1728.org/polygon.htm

Answer 2

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