What's the ROI formula. I have this:Operating Income / Avr. Total Assets, but I was looking online at this one:ROI = [(Payback - Investment)/Investment)]*100

I'm trying to solve this problem:

Recreation Equipment Company has several divisions that are investment centers. Data for the Boat Division and the Trailer Division are shown here:

	Boat Division	Trailer Division
Operating income	$90,000	$36,000
Total assets at Jan 1	$670,000	$230,000
Total assets at Dec 31	$710,000	$220,000

With regard to the efficient use of assets, which division has a higher ROI (show your calculations)

I get 13.04% and 16%

Thank you