200 logs are stacked in the following manner: 20 logs in the bottom row, 19 in the next row, 18 in the row next to it and so on (see Figure). In how may rows are the 200 logs placed and how many logs are in the top row?

Explanation

Here, a is the first term, d is a common difference and n is the number of terms.


It can be observed that the number of logs in rows are forming an A.P. `20, 19, 18, ...`


For this A.P.,


...