a) 50 % because when the loci are at opposite ends of a chromosome they behave as if they were on different chromosomes.
Beginning with 100% | recombination results in 50% | and 50% |
The resulting cross gives results almost identical to a normal Mendelian dihybrid cross, which can be symbolized as follows:

recombinant genotypes |
b) You would assume that these genes were on separate chromosomes since they appear to segregate independently even though they are linked.