For most gases at standard or near standard conditions, the relationship among pressure, density, and temperature is given by the perfect gas equation of state: p = pRT, where R is the specific gas constant. For air at near standard conditions, R = 287 J/(kg ∙ K) in the International System of Units and R = 1716 ft ∙ lb/(slug ∙ °R) in the English Engineering System of Units. (More details on the perfect gas equation of state are given in Chap. 7.) Using the above information, consider the following two cases: 

(a) At a given point on the wing of a Boeing 727, the pressure and temperature of the air are 1.9 x 10⁴ N/m² and 203 K, respectively. Calculate the density at this point. 

(b) At a point in the test section of a supersonic wind tunnel, the pressure and density of the air are 1058 lb/ft² and 1.23 x 10^-3 slug/ft³, respectively. Calculate the temperature at this point.