x + 2x + 2x + (x + 30∘30^{\circ}30∘) + (x + 20∘20^{\circ}20∘) + (x - 10∘10^{\circ}10∘) = (2n - 4) x 90∘90^{\circ}90∘
8x + 50 ∘^{\circ}∘ - 10∘^{\circ}∘ = (2 x 6 -4) x 90∘^{\circ}∘
8x + 40∘^{\circ}∘ = 8 x 90∘^{\circ}∘ = 720∘^{\circ}∘
8x = 720∘^{\circ}∘ - 40∘^{\circ}∘ = 680∘^{\circ}∘
x = 680∘8\; \frac{680^{\circ}}{8}8680∘
= 85∘^{\circ}∘
