27 = 100% how much % is 17?
\(x\% \;of\;27=17\\ \frac{x}{100} \;\times\;27=17\\ \frac{x}{100}=\frac{17}{27}\\ x=\frac{17}{27}\times 100\\ x\approx 62.96\% \)
check
62.97/100*27 = 17.0019 near enough :)