The weights of 4 boxes are 20, 30, 50 and 70 kilograms. Which of the following cannot be the total weight, in kilograms, of any combination of these boxes and in a combination a box can be used only once?
If the first 10 terms and the last 10 terms of the given expression are interchanged in such a way that the first term is interchanged with the last, the second with the second last, the third with the third last and soon, what will the fifth term from the right be in the new arrangement?