Phosphorus and bromine react to form phosphorus tribromide, like this: P4(g) + 6Br2(g) 4PBr3(g) 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
P4	50.1atm
Br2	19.6atm
PBr3	61.5atm

Calculate the value of the equilibrium constant Kp for this reaction. Round your answer to 2 significant digits.