The father's code

On his deathbed, the father gave his son a piece of paper, Ben quickly grab the paper and reads it. "3.70 =13.20" exclaimed the young man, "what is this father?", knowing that his father spends his time discovering the secrets on earth, he quickly assume that this is a code of his last discovery. After his father dies, Ben spent most of his life solving the equation. He becomes a great mathemathician, historian and a well-known archeologist but in spite of his success in life, he can't solve his father's equation. One day, he realized that if no one can help him in the present time, maybe the people in the past can solve it. After several years, he successfully build a time machine. As he travels in the past, he saw Isaac newton and gave him the piece of paper, "sorry i dont know what it implies" said Newton, with great disappointment on his face, he travels again and saw Albert Einstein, "sorry gentleman, but this equation is impossible". He goes back again in the past and met other several men of mathematics, but no to avail. Admitting his defeat, he went to a local bar sobing and distraught. The bartender asks "Ben what's the problem?", "no one can help me" Ben replied. "you know, Ben, my mother in mexico always tells me not to give up, don't give up Ben, you can tell me your problem". Ben immediately grab the piece of paper and ask "can you solve it?". as he reads the equation the bartender laughs.