Solution -
SP of the article = 1800
Profit of A = 1800 × (20/100)
= Rs. 360
And,
Profit % = [(SP - CP) / CP] × 100
20 = [(1800 - CP) / CP] × 100
20/100 = [(1800 - CP) / CP]
CP = 5(1800 - CP)
CP = 9000 - 5CP
CP + 5CP = 9000
6CP = 9000
CP = 9000/6
CP = 1500
Thus,
Profit of B = SP - CP
= 1800 - 1500
= 300
Therefore,
The difference in profits of A and B = Profit of A - Profit of B
= 360 - 300
= 60
Hence,
The correct answer is option (b) Rs. 60.