converting returns from us to cad

Hello, I am trying to convert historical returns of the S&P 500 Total Return index into CAD returns. Can someone remind me of the calculation please? I have not had any luck searching the internet and my old books are at home. Benchmark return of S&P TR = 15.06% % FX change (appreciation of CAD)= 4.87% the client has reported a bench mark return of 9.72%. I get close by subtracting 4.87 from the 15.06, however I am still off by a bit. I think there is more to the formula though then just subtracting the gain. Any help is appreciated. Thanks

1.1506 / 1.0487 = 9.72%

wow…its really been a while… thanks very much!