A retail fruit vendor buys pineapples at a score for Tk. 200, and retails them at a dozen for Tk. 156. What % was his gain or loss?

Question: A retail fruit vendor buys pineapples at a score for Tk. 200, and retails them at a dozen for Tk. 156. What % was his gain or loss?

Solution:
C.P of 1 pineapple = 220/score = 200/20 = 10 [Note: 1 score = 20 nos.]
S.P of 1 pineapple = 156/dozen = 156/12 = 13.
∴ Profit = 13 - 10 = 3
∴ % Profit = 100 × (3/10) = 30%