You say you're 100% certain that the reimbursement has been taxed. If that's true, you do NOT have to report the tuition reimbursement and can claim the entire $2051 for the tuition credit.
But you probably shouldn't be 100% sure. As KrisD1 said, the opposite is usually true. Any amount under $5250 is usually tax free. As such, you cannot claim (for the credit) any tuition paid by tax free employer reimbursement.
