A bookshop had science and art books in the ratio of 2:5. By the end of the week, 20% of both type of books were sold and 2240 books were unsold. How many science books were there at the starting?  Pick one.
A) 200	B) 300	C) 400	D) 800	E) 900
science books sold = 2x × 0.2 = 0.4x   science books unsold = 2x – 0.4x = 1.6x   art books sold = 5x × 0.2 = x   art books unsold = 5x – x = 4x   total books unsold = 1.6x + 4x = 5.6x   5.6x 1.6  + 4= 
<gadget id="calculator">1.6  + 4</gadget>
<output>5.6</output>
5.6x   5.6x= 2240   x = 400   2x science = 800   800
<result>D</result>
A bookshop had science and art books in the ratio of 2:5. By the end of the week, 20% of both type of books were sold and 2240 books were unsold. How many science books were there at the starting?