Need help understanding seller financing terms

[Anthony O.]

Im working on negotiating a deal and the seller offered the following terms. I need help understanding exactly how this would work out:

"Balance between your cash and agreed upon price would be financed at 7.5% with payments of $300 a month."

Is that 7.5% +300 per month or 300 per month for the duration of the loan with 7.5% per year?