Sum of interior angles = (2n - 4) 90∘^{\circ}∘
For perntagon, n = 5
Sum of interior angles = 6 x 90∘^{\circ}∘ = 540∘^{\circ}∘
6x + 6y = 540∘^{\circ}∘
6(x + y) = 540∘^{\circ}∘
x + y = 540∘6\frac{540^{\circ}}{6}6540∘ = 90∘^{\circ}∘
y = 90∘^{\circ}∘
y = 90 - x
