Two oranges, three bananas and four apples cost Rs. 15. Three oranges, two bananas and one apple cost Rs. 10. I bought 3 oranges, 3 bananas and 3 apples. How much did I pay ?

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

$$\Rightarrow$$ 2o + 3b + 4a = 15..........(1)

Also given, Three oranges, two bananas and one apple cost Rs. 10

$$\Rightarrow$$ 3o + 2b + a = 10............(2)

Adding (1) and (2), we get,

5o + 5b + 5a = 25

$$\Rightarrow$$ 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$$\times$$ 5 = Rs. 15