Find the number of terms in the following A.P. :
`18, 15(1)/(2), 13 .. -47`.

Explanation

To find the number of terms in the given arithmetic progression (A.P.): 18, 15.5, 13, ..., -47, we can follow these steps:

### Step 1: Identify the first term (a) and the common difference (d)
The first term \( a \) is given as:
\[ a = 18 \]

The second term is:
\[ a_2 = 15.5 = \frac{31}{2} \]
...