How to figure out "L"

Answer:
Add 30 to each side so L+L/3+L=630 then Multiply each side by 3 so 3L+L+3L=630 then add together the L's to get 7L=630 then divide by 7 so L=90
[tex]L + \frac{L}{3} + L - 30 = 600\\\\L + \frac{L}{3} + L = 600 + 30\\\\L + \frac{L}{3} + L = 630\\\\2L + \frac{L}{3} = 630\\\\\frac{6L}{3} + \frac{L}{3} = 630\\\\\frac{7L}{3} = 630\\\\7L = 630 * 3\\\\7L = 1890\\\\L = \frac{1890}{7} \\\\L = 270[/tex]