My son is in XI (Science with maths), but is not able to cope up with it and want to change the subjects. What should he do? He's confused.

Seek guidance in school, and ask if they can accommodate him in the courses that he likes. They might take him after an undertaking. But, your son wouldn't have to repeat a year.

It depend upon his dream. If he wants to fulfill it, then he have to come up with it. And, if not, then go for commerce or arts. But, remember all are tough in their respective fields.