In a shop, 40% socks are white and rest are black. 60% socks are made of cotton and rest are made of wool. 25% white socks are made of cotton and 20 of the black socks are made of wool. How many black socks X are made of cotton?
Options:	A) 100	B) 80	C) 60	D) 50	E) 25
I'll prefer to solve this with plug n play method.   As we know, White Cotton socks are only 25% and Total Cotton socks is 60% - Hence Black Cotton socks X has to be [highlight]HIGH[/highlight]number. Thats why we've to pick high number... say 100 or 80.   100 fits perfectly after relevant calculations. Hence answer 100.
<result>A</result>
In a shop, 40% socks are white and rest are black. 60% socks are made of cotton and rest are made of wool. 25% white socks are made of cotton and 20 of the black socks are made of wool. How many black socks X are made of cotton?