What is the total amount and benefit type for the period 01/06/2003 until 31/01/2005?

Expenditures form an arithmetic progression: first term $a=4000$, common difference $d=500$, $n=12$ terms, last term $l=9500$.

$$\begin{align*} S_n &= \frac{n}{2} (a + l) \\ S_{12} &= \frac{12}{2} (4000 + 9500) \\ &= 6 \times 13500 \\ &= 81000 \end{align*}$$

Total expenditure = Rs. $\mathbf{81000}$

Incomes form an arithmetic progression: first term $a=5000$, common difference $d=500$, $n=12$ terms, last term $l=10500$.

$$\begin{align*} S_n &= \frac{n}{2} (a + l) \\ S_{12} &= \frac{12}{2} (5000 + 10500) \\ &= 6 \times 15500 \\ &= 93000 \end{align*}$$

Total income = Rs. $\mathbf{93000}$

$$\begin{align*} \text{Profit} &= \text{Total income} - \text{Total expenditure} \\ &= 93000 - 81000 \\ &= 12000 \end{align*}$$

Net profit = Rs. $\mathbf{12000}$

12000