Answer:
30
Explanation:
x = original number of stamps
x+23 (added 23 stamps to the collection)
3(x+23) tripled in number
3(x+23) = 159
Divide each side by 3
3(x+23)/3 = 159/3
x+23=53
Subtract 23 from each side
x+23-23 = 53-23
x = 30
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