John had a stock of 900 books in his bookshop. He sold 75 on Monday, 50 on Tuesday, 64 on Wednesday, 78 on Thursday and 135 on Friday. What percentage of the books were not sold? Pick one:	A) 50.4%	B) 23.8%	C) 66.5%	D) 34.9%	E) 55.3%
Let N be the total number of books sold. Hence   N = 75 + 50 + 64 + 78 + 135= 
<gadget id="calculator">75 + 50 + 64 + 78 + 135</gadget>
<output>402</output>
402   Let M be the books NOT sold   M= 900 - N = 900 - 402= 
<gadget id="calculator">900 - 402</gadget>
<output>498</output>
498   Percentage   Books not sold / total number of books= 498/900 = 0.553 = 55.3%   correct answer 55.3%
<result>E</result>
John had a stock of 900 books in his bookshop. He sold 75 on Monday, 50 on Tuesday, 64 on Wednesday, 78 on Thursday and 135 on Friday. What percentage of the books were not sold?