It sounds as you signed rental agreement with the landlord and signed sub rental agreement with a student.
If that is correct - you need to report rental income and rental expenses on the schedule E - http://www.irs.gov/pub/irs-pdf/f1040se.pdf - and will attach it to your tax return
Your rental income would be $350*12= $4200 - do not include security deposit if any.
Your rental expenses should d be prorated according to rental footage percentage: (footage of rented rooms plus 1/2 of common places) divided by total apartment footage.
The difference between the rental income and the rental expenses will be your rental income/loss and will be reported on the from 1040 - http://www.irs.gov/pub/irs-pdf/f1040.pdf line 17 - if zero - report zero.