PLEASE HELP

Dear Sir Moffat,

I have been battling with this question for days now. It was given to me as an assignment. It is not part of ACCA syllabus. I will appreciate if you could be kind enough to help out.

John plc is considering acquiring matron plc. They are both in related line if business. Matron plc presently has a cash flow of $3million after tax per ammunition with the acquisition. Synergism would be expected to result in a growth rate of this cash flows of 10% per annum for 8yrs after which the cash flow stream would stop growing. John PLC will need to invest on average $1.2million annually. To be conservative, john plc for the purpose of analysis intends to limit its calculation of cash flows to 20years.
If the required rate of return in matron plc is 20%, calculate the maximum price John plc should pay to purchase matron plc

I solved it this way. Am I right?

Year 1-20 Cashflow outflow (1,200,000) * 4.870 = (5,844,000)
Year 1-8 CashInflow (Using annuity formula) = 15,044,092.6
Year 9-20 Cash Inflow 6430766.43 * 1.033 = 6642981.7

Maximum Amount = $15843074.3

Am I correct Sir?