Please help my son with #3

Answer:   14/15 more pints of strawberries than grapesStep-by-step explanation:You want to find the difference between 2 1/3 and 1 2/5. There are several ways to do this. One is to use a common denominator for the fractions. Here, a convenient denominator is 3·5 = 15. This lets us write the problem as ...   2 5/15 - 1 6/15   = (2 -1) + (5/15 -6/15)   = 1 - 1/15 . . . . of course there are 15/15 in 1, so subtracting 1 of them gives...   = 14/15Kelly uses 14/15 more pints of strawberries than of grapes in her juice._____Comment on solution detailsWe have rewritten the fraction 1/3 as 5/15. We can do this by multiplying 1/3 by 1, where 1 is in the form 5/5:   (1/3) = (1/3)·1 = (1/3)·(5/5) = (1·5)/(3·5) = 5/15Similarly, we have rewritten the fraction 2/5 by multiplying it by 3/3:   (2/5) = (2/5)·(3/3) = 6/15__Both numbers can be converted to improper fractions:   2 1/3 = (2·3+1)/3 = 7/3   1 2/5 = (1·5+2)/5 = 7/5Then the difference can be found using the formula ...   a/b - c/d = (ad -bc)/(bd)   7/3 -7/5 = (7·5 -7·3)/(3·5) = (35 -21)/15 = 14/15