The last time Rohit bought Diwali cards, he found that the four types of cards that he liked were priced Rs.9.00, Rs.7.00, Rs.4.50 and Rs.5.50 each. As Rahul wanted 30 cards, he took five each of two kinds and ten each of the other two, putting down the exact number of 10 rupees notes on the counter payment. How many notes did Rohit give? Choose the correct option.
A) 15	B) 10	C) 22	D) 20	E) 18
Explanation :   Let the four cards be a, b ,c and d. 'x' be the number of notes.   Then, according to the question,   =&gt; 5a + 5b + 10c + 10d = 10*x.   =&gt; a + b + 2(c+d) = 2 * x . -----------------------------(i)   Since, a + b = 9+7= 
<gadget id="calculator">9+7</gadget>
<output>16</output>
16   And,=&gt; c + d = 4.50+5.50= 
<gadget id="calculator">4.50+5.50</gadget>
<output>10</output>
10 .   Putting these values in (i), we get :-=&gt; 16 + 2 *10 = 2 * x.   =&gt; x = 18.   Answer :18
<result>E</result>
The last time Rohit bought Diwali cards, he found that the four types of cards that he liked were priced Rs.9.00, Rs.7.00, Rs.4.50 and Rs.5.50 each. As Rahul wanted 30 cards, he took five each of two kinds and ten each of the other two, putting down the exact number of 10 rupees notes on the counter payment. How many notes did Rohit give?