ROI and ROE calculations for a flip

[Account Closed]

A friend of mine asked about calculating ROI/ROE for a flip he completed in April.

Details:
Source of funds from HELOC interest only.
Rate at prime rate + 1/1 a point (4%).
Purchase price $128,000
Purchase date 01/21/2016
Sold price $179,000
Sold date 04/21/2016
Cost of purchase and sale (includes attorney fees, title insurance, RE commission etc) $8,348
Repair and Holding cost (includes taxes, insurance, interest etc) $14,876
Net profit $27,776

Since my friend did not put any money out of his pocket (money required to pay minimum monthly interest dues were pulled off from HELOC as well), there is no equity out of his pocket. So how do you calculate the ROE?

I calculated the % ROI (annualized) (Sold price - Purchase price) / (Purchase Price + Total Expenses) and annualized to a year which come to about 73%

Is the way we are calculating ROI and stating you cannot calculate ROE since you did not put any equity in it, is correct way to look at this?