if 5 % more is gained by selling an article for rs . 600 than by selling it for rs . 580 , the cost of the article is ?
"let c . p . be rs . x . then , 5 % of x = 600 - 580 = 20 x / 20 = 20 = > x = 400 answer : c"
divide(subtract(600, 580), divide(5, const_100))