How many terms of the A.P. `-6, -(11)/2,\ -5,...`` are needed to give the sum -25?

Explanation

To solve the problem of finding how many terms of the arithmetic progression (A.P.) `-6, -11/2, -5, ...` are needed to give the sum of `-25`, we can follow these steps:

### Step 1: Identify the first term and common difference
The first term \( a \) of the A.P. is:
\[ a = -6 \]
To find the common difference \( d \), we can subtract the first term from the second term:
...