A person ordered 5 pairs of black socks and some pairs of brown socks. The price of a black pair was thrice that of a brown pair. While preparing the bill, the bill clerk interchanged the number of black and brown pairs by mistake which increased the bill by 100%. What was the number of pairs of brown socks in the original order?
Price of Brown socks = p
Price of Black socks = 3p
Let number of brown socks ordered be n.
Wrong Bill is 100% more means it is twice than the correct bill.
n*3p + 5*p = 2(n*p + 5*3p)
3n + 5 = 2n + 30
n = 25
The correct option is B.