Chemistry help?

The value of Kp for the reaction below is 4.750*10^-6 at 75 degrees Celsius
NO(g)+1/2O2(g)=NO2(g)
At equilibrium, what is the ratio of Pno2 to Pno in air at 75 degrees Celsius? Assume that Po2=.21atm and does not change. Round to three significant figures.