같이 장사하게되는 오래 알고 지낸 형한테 2천만원 정도 빌려 주게 되었는데 빌려주는데는 크게 거부감이 없는데 그렇다고 안받아도 될정도의 금액도 아니고..사람일 어찌될지 모르니.. 그렇다고 공증이나 이런거 하자고 하기도 그렇고..계좌 송금 기록 만으로도 빌려줬다는 증거는 될수 있나요?