You are on vacation in the far-off land of Nauttareelpleys (NRP), and have rented a car. The tires seem a little flat, so you decide to add some air. Unfortunately, the recommended tire pressure shown on the door frame is listed in official NRP units of balloons (bl), where 1 bl=1 dog/(arm minute2) (1 dog=12 kg, 1 arm = 684 mm), while your tire gauge is in PSI (pounds per square inch). If the tire pressure on the door frame is 50.9 Mbl (megaballoons), what does this correspond to in PSI?

Note that 1 pound = 4.448 Newtons (N), 1 N=1 kg m/s2, and 1 inch = 2.54 cm.