Four Possibly Different Albino Strains of Neurospora Were Each Crossed $\times$

Essay

Four possibly different albino strains of Neurospora were each crossed to wild type.All crosses resulted in 1/2 wild-type and 1/2 albino progeny.Crosses were made between the first strain and the other three with the following results:
1 $\times$ 2: 975 albino : 25 wild type
1 $\times$ 3: 1000 albino
1 $\times$ 4: 750 albino : 250 wild type
Which mutations represent different genes and which genes are linked? How did you arrive at your conclusions?