The last time Rahul bought Diwali cards, he found that the four types of card that he liked were priced Rs. 2.00, 3.50, 4.50 and 5.00 each. As Rahul wanted 30 cards, he took five of two kinds and ten each of the other two, putting down the exact number of 10 rupee notes on the counter payment. How many notes did Rahul give?
a) 8
b) 9
c) 10
d) 11
Ans: d) 11
By trail and error, verify that buying 5 cards each priced at 3.50 and 4.50 and 10 cards each priced at 2.00 and 5.00 costs Rs.110, which can be paid in 11 ten rupee notes.
