Phosphorus and bromine react to form phosphorus tribromide, like this: PA(g) + 6 Br,(9) - 4 PBr;(9) Also, a chemist finds that at a certain temperature the equilibrium mixture of phosphorus, bromine, and phosphorus tribromide has the following composition: compound pressure at equilibrium PA 42.0 atm Br, 55.6 atm PBI3 29.6 atm Calculate the value of the equilibrium constant X, for this reaction. Round your answer to 2 significant digits. K = Il