Over the summer you discover a three eyed, fly with legs coming out of its head instead of antennas. To determine how close these alleles (eye trait, legs-on-head trait) are to each other on the same chromosome, you cross this true breeding fly with a normal (2-eyed, antennae) fly. The F1 generation is all wildtype. You then backcross an F1 animal to the original mutant animal which generates; 500 normal flies, 50 2-eyed, head-legged flies, 76 three-eyed, antenna flies and 400 three-eyed, head-legged flies. How far apart are these genes