How do I process this in excel? I'm confused by the highlighted step.

P0(1+r)n$35(1+r)5(1+r)5(1+r)=Pn=$56.38=1.610857143=51.610857143(1+r)rrr=1.1000474=1.10004741=0.1000474=10% Hence, the true annual rate of return is