OK, so a simpler way to describe what they're asking:
The bin size for the table you have is 12. So you have 10 frequency bins, each 12oz wide, covering a total range of 120oz (40-168).
What the question wants you to do is collapse the data into larger bins, 24oz across. Simply sum the frequencies in the two smaller bins to find the frequency in the new larger bin. This will leave you with 5 bins total:
48-72: 15+24 = 39
72-96: 41+67 = 108
96-120: 119+184 = 303
120-144: 142+26 = 168
144-168: 5+2 = 7
For part b) all you have to do is create a histogram of these larger frequency bins. So you'll have 5 vertical bars (one for each bin) and the height of each bar will be the total frequency (from the table above, e.g. the middle bar will have height 303). Make sure the bars don't have gaps between them, since it's a histogram!