[tex] \frac{3}{2} \times b + (b + 45) + 90 + (2 \times b - 90) + b = 540 \\ \frac{3 \times b}{2} + b + 45 + 90 + 2 \times b - 90 + b = 540 \\ \frac{3 \times b}{2} + 4 \times b + 45 = 540 \\ \frac{3 \times b}{2} + \frac{8 \times b}{2} = 540 - 45 \\ \frac{11 \times b}{2} = 495 \\ 11 \times b = 2 \times 495 \\ 11 \times b = 990 \\ b = \frac{990}{11} \\ b = 90[/tex]
