Return on investment

Hi all

I'm looking at buying a family members property but want to rent it out for the first year

I've done a few sums to work out my return on investment but they seem high have i made a mistake

they go as follows

purchase price............................................. .............................. £157k
amount invested
(including fees, deposit, refurb costs, stamp duty)................. £32555
Annual income from rent.............................................. ...........£9600
Interest paid on mortgage (annual).......................................... £4806
(mortgage required £133k @ 3.59%)

profit = annual rent - interest on loans = £4794

ROI = profit / total invested x 100

so ROI is 14% surely my sums are wrong it seems too good

I know this doesn't take into account for buildings insurance and maintenance costs though

cheers