the mean daily profit made by a shopkeeper in a month of 30 days was rs . 350 . if the mean profit for the first fifteen days was rs . 285 , then the mean profit for the last 15 days would be
"average would be : 350 = ( 285 + x ) / 2 on solving , x = 415 . answer : d"
divide(subtract(multiply(30, 350), multiply(15, 285)), 15)