Ting Ting has 99 beads more than Roxanne.
Ting Ting's = 165 beads
Sherrie : has 4/5 beads that of Ting Ting's
165 * 4/5 = 660 / 5 = 132 beads
Roxanne : has 1/2 as many beads as Sherrie
132 * 1/2 = 132 / 2 = 66 beads
Ting Ting's beads - Roxanne's beads = difference
165 - 66 = 99 beads.
Ting Ting has 99 beads more than Roxanne.