A physiologist on a space flight to a distant planet. You discover intelligent humanoid aliens inhabiting the planet, and they willingly submit to your tests. You discover that the alien's kidney handles the sugar alcohol mannitol just like our kidneys handle inulin. You also test the alien for its renal handling of glucose. The data from that experiment are: Plasma level (constant over 24 hrs): 6 g/dL of mannitol and 2 g/dL of glucose; 24 hr. urine sample: volume of 2 L, containing 144 g mannitol and 52 g glucose.
What is the alien's glomerular filtration rate?