Solution:Let the cost price of the article = Rs. ‘100y’
ATQ:
100y × 1.15 - 100y × 0.78 = 518
115y - 78y = 518
37y = 518
y = (518/37) = 14
So, cost price of the article = 100y = Rs. 1,400
From I:
Marked price of the article = 1400 × 1.5
= Rs. 2,100
Selling price of the article = 2100 × 0.8 = Rs. 1,680
So, option I is true.
From II:
Marked price of the article = 1400 + 350
= Rs. 1,750
Selling price of the article = 1750 × 0.96
= Rs. 1,680
So, option II is true.
From III:
Marked price of the article = 1400 × 1.3
= Rs. 1,820
Selling price of the article = 1820 - 200 = Rs. 1,620 ≠ 1680
So, option III is false.