Today I am giving the answer and How did I solve it.
My first and clear approach was identified a total sum of 1 to 10 which is 55. But if we need to 4 pieces of 15 means total 60.
And sum of 11 and 12 is 23 which is not so helpful. But cleverly if you look we only need to add 5 more to 55. And sum of each digits of 11 and 12 is 5. But cutting them in half make available to sum individually.