The optimum profit is achieved by buying all 5 Apartments plus 1 Condo. The reason is as follows:
The profit margin on the apartments is the highest. i.e. 13.3%, (see the table below) so you invest as much as you can in Apartments. Since there are only 5 of them you will be spending 5 x $90,000 = $450,000, leaving $50,000.
Your next best profit category is the Condos (at 12%). So you invest the remaining $50,000 in Condos. That would buy you 1 Condo. The overall profit in this case is $66,000 which is 13.2% return on investment.
Here is an image of the excel table:
And here is the excel file.
Hope this helps.
Thanks for the accept. Go ahead and post the other questions.