The cost price of 10 books is equal to the selling price of 9 books. Find the gain percent?A10 1/9%B9 1/9%C11 1/9%D10%Answer: C. 11 1/9%Read Explanation:Gain% = (x - y) / y * 100% =(10-9) /9 * 100% =100/9% = 11 1/9% Open explanation in App