In an A. P. :
given `l = 28, S = 144,` and there are total 9 terms Find a.

Answer

To solve the problem, we need to find the first term \( a \) of an arithmetic progression (A.P.) given the last term \( l = 28 \), the sum \( S = 144 \), and the number of terms \( n = 9 \).

### Step-by-step Solution:

1. **Identify the given values**:
- Last term \( l = 28 \)
- Sum of the terms \( S_n = 144 \)
- Number of terms \( n = 9 \)

2. **Use the formula for the sum of an A.P.**:
The formula for the sum of the first \( n \) terms of an A.P. is given by:
\[ S_n = \frac{n}{2} (a + l) \]
Here, \( S_n = 144 \), \( n = 9 \), and \( l = 28 \).

3. **Substitute the known values into the formula**:
\[ 144 = \frac{9}{2} (a + 28) \]

4. **Multiply both sides by 2 to eliminate the fraction**:
\[ 288 = 9(a + 28) \]

5. **Divide both sides by 9**:
\[ 32 = a + 28 \]

6. **Solve for \( a \)**:
\[ a = 32 - 28 \]
\[ a = 4 \]

### Final Answer:
The first term \( a \) of the A.P. is **4**.