Part A: it would take him 12 days to read 4 books since it takes him 3 days to read one book (3x4=12)
Part B: If Rusin reads 1/3 of a book a day, it takes him 3 days to read 1 whole book, or 3/3 this multiplied by 10=30 days. Victoria on the other hand reads 1/4 of a book a day, so it takes her 4 days to read one book. 4 days x10 books=40 days. Therefore it would take Victoria 10 days longer.
