U-tube

Initially, the U-tube shown above is filled with water, and the level on each side is $$\ell_0 = \SI{5}{\centi\meter}.$$ After some oil is poured on side $$A,$$ the level on that side becomes $$L_A = \SI{7.3}{\centi\meter}.$$

What is $$L_B$$ $$($$in $$\si{\centi\meter})?$$

Assume that the water and oil do not mix, and that their densities are related by $$\rho_\textrm{oil} = 0.85\rho_\textrm{water}.$$

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