At equilibrium for the reaction

A + 2B --> C + D
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the concentration of A is 0.579 mol/L, the concentration of B is 0.598 mol/L, the concentration of C is 0.465 mol/L, and the concentration of D is 0.608 mol/L. What is the equilibrium constant for this reaction?

Write the Keq expression and plug each concn into that and calculate. If this is a problem for you tell us exactly what you don't understand.