Explanation:
To find the purchase figure for the month, we use the Trading Account formula to compute Cost of Goods Sold (COGS) first, and then use that to back-calculate purchases.


Step 1: Use the Trading Account Formula

Trading Account formula:

\[
\text{Sales} - \text{Cost of Goods Sold (COGS)} = \text{Gross Profit}
\]

We are given:
- Sales = ₦11,000
- Profit = ₦900
- Other expenses = ₦2,000

Since Net Profit = Gross Profit - Expenses, we can calculate Gross Profit:

\[
\text{Gross Profit} = \text{Net Profit} + \text{Expenses} = ₦900 + ₦2,000 = ₦2,900
\]

Now calculate COGS:

\[
\text{COGS} = \text{Sales} - \text{Gross Profit} = ₦11,000 - ₦2,900 = ₦8,100
\]



Step 2: Use the COGS Formula to Find Purchases

\[
\text{COGS} = \text{Opening Stock} + \text{Purchases} - \text{Closing Stock}
\]

We are given:
- Opening stock = ₦2,400
- Closing stock = ₦6,400
- COGS = ₦8,100

Now plug in values:

\[
8,100 = 2,400 + \text{Purchases} - 6,400
\]

\[
8,100 = \text{Purchases} - 4,000
\]

\[
\text{Purchases} = 8,100 + 4,000 = ₦12,100
\]