now.. if you check the picture below
notice that, "x" and "y" are just "supplementary" angles
so.. what the dickens is "x" anyway?
well, "x" is an internal angle to the pentagon
and [tex]\bf \textit{sum of all interior angles in a polygon}\\\\
180(n-2)\qquad
n=\textit{number of sides}[/tex]
so.. this polygon is a pentagon, or PENTA=5, 5 sides
so all internal angles add up to 180(5-2) or 180*3 = 540
now, check the angle on the bottom-left-corner, is a right-angle
so... you already have 4 angles given inside
so x + 80 + 160 + 100 + 90 = 540
solve for "x"
what about "y"? well, y = 180 - x
