Ricardo, mass 86 kg and Carmelita, who is lighter, are enjoying Lake Merced at dusk in a 30 kg canoe. When the canoe is at rest in the placid water, they exchange seats, which are 3.0 m apart and symmetrically located with respect to the center of the canoe. Ricardo notices that the canoe moved 50.3 cm relative to a submerged log during the exchange and calculates Carmelita's mass, which she has not told him. What is it?