Students were asked to choose their favorite subject and, and 3/5 choose either history or biology. If 1/5 of the students choose history, what fraction choose biology?
3/5 chose either history or biology, and 1/5 chose history. If we want to find what fraction chose biology, we just subtract those who chose history for those who chose either one. 3/5 minus 1/5 is 2/5.
