the ratio between the sale price and the cost price of an article is 9 : 7 . what is the ratio between the profit and the cost price of that article ?
"let c . p . = rs . 7 x and s . p . = rs . 9 x . then , gain = rs . 2 x required ratio = 2 x : 7 x = 2 : 7 answer : b"
divide(subtract(9, 7), 7)