At 10 GHz and a certain incidence angle, the apparent brightness temperatures of sea water, first-year ice and multi-year ice are 80 K, 252 K and 200 K respectively. At 37 GHz these figures become 119 K, 253 K and 168 K. If a microwave radiometer measures a brightness temperature of 180 K at both frequencies, what are the fractions of open water and multi-year ice present in the IFOV?