Answer: CGST = ₹ 900 and SGST = ₹ 900
The tax invoice issued to the customer is for the sale of ₹ 10,000.
\[ \text{GST} = 10000 \times \frac{18}{100} = ₹\,1800 \]
CGST = SGST = ₹ 900 (9% each).
Note: ITC on the purchase is \(18\% \text{ of } 6000 = ₹\,1080\), so the GST actually payable to the government is \(1800 - 1080 = ₹\,720\) (₹ 360 CGST + ₹ 360 SGST), but the invoice shows ₹ 900 each.