Sum of all interior angles of a polygon
180( n - 2) where n = number of sides in the polygon
now, if n = 19, the polygon has 19 sides, then 180( 19 - 2)
Take the square root. The opposite of squaring something is taking the root :)
√x^2 = √26
x = √26
x = 5.099...
OR leave it if your teacher doesn't want a decimal since it can't be simplified anymore
5x = 15
x = 3
3(3) - 5y = -16
9 - 5y = -16
5y = -16 - 9
5y = - 25
y = - 5
(3, -5)
