The kind of ROI Luis demonstrates is : Positive ROI
A positive ROI is defined as when the cost of a financial decision/step is lower than the gain of a financial decision.
Luis takes a loan to help him earn a certificate, the certificate he earns has helped him earn a good salary job which he can use to repay the loan.
Therefore in the long term Luis will have a positive return on investment on his financial decision.
Hence we can conclude that the kind of ROI Luis demonstrates is Positive ROI.
Learn more about ROI here : brainly.com/question/23603222