Issue with Course Purchase:
The issue you are facing with only the math subject being accessible after purchasing the 3rd class course can be frustrating. It is important to address this concern and find a solution to ensure you have access to all the subjects you paid for.

Possible Reasons:
There could be several reasons for this issue. It is possible that there may be a technical glitch on the platform preventing the other subjects from opening. It is also possible that there could be a mistake in the course setup or access permissions.

Steps to Resolve:
1. Contact Customer Support: The first step you should take is to reach out to the customer support team of the platform where you purchased the course. They will be able to investigate the issue and provide you with a solution.
2. Provide Proof of Purchase: Make sure to have your purchase receipt or any other proof of payment handy when contacting customer support. This will help expedite the process of resolving the issue.
3. Ask for Refund or Access to Other Subjects: If the issue cannot be resolved promptly, you can request a refund for the course or ask for access to the other subjects that are not opening. Most platforms have policies in place to address such situations.
4. Follow Up: If the issue is not resolved in a timely manner, make sure to follow up with customer support to ensure that your concern is being addressed properly.

Conclusion:
It is important to address this issue promptly to ensure that you are getting the value for the course you purchased. By following these steps and communicating effectively with the customer support team, you should be able to resolve the issue and gain access to all the subjects included in the course.