How much should I offer for a business?

Benjamin O’Henry owns and operates O’Henry's Data Services and wants to sell the business. I am interested in purchasing the business and obtain its most recent monthly unadjusted trial balance. I am willing to pay 20 times the monthly net income I could expect to earn from it and his asking price is the ending capital. After computing the net income, I came up with $6350. After multiplying this number by 20 I found that I would be willing to pay $127000 for the business. I computed the ending capital and came up with $144750. Under these conditions, how much should I offer O'Henry? Give your reason.