Let the cost of each orange, banana and apple be Rs. 'o' , 'b' , and 'a' respectively. Given, Two oranges, three bananas and four apples cost Rs. 15 2o + 3b + 4a = 15..........(1) Also given, Three oranges, two bananas and one apple cost Rs. 10 3o + 2b + a = 10............(2) Adding (1) and (2), we get, 5o + 5b + 5a = 25 o + b + a = 5 Then the cost of three oranges, three bananas and three apples is given as 3o + 3b + 3a = 3 [o + b + a] = 3 × 5 = Rs. 15