Answer:
Let j = number of stickers James has
d = number of stickers David has
(j - 40)/(d + 40) = 1/3
3(j - 40) = d + 40
3j - 120 = d + 40
3j - d = 160
(j - 60)/(d + 60) = 1/11
11(j - 60) = d + 60
11j - 660 = d + 60
11j - d = 720
3j - d = 160
11j - d = 720
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8j = 560
j = 70, d = 50
James has 70 stickers, and David has 50 stickers.