# speed control loop percent error

I'm having trouble understanding the percent error from the following closed loop feedback equations. $w =1$ is the road grade change and $r=65$ is the speed control input, and given closed loop output speed $Y_{cl}$ and closed loop error $e_{cl}$: $$\ Y_{cl} = \frac{100}{101}r-\frac{5}{101}w\$$ $$\ e_{cl} = \frac{r}{101}+\frac{5}{101}w\$$ My question is why is the correct percent error equation as follows: $$\%error = 100\frac{\frac{100}{101}r - (\frac{100}{101}r - \frac{5}{101}w)}{\frac{100}{101}r} \$$ and not: $$\ 100\frac{e_{cl}}{r}\$$

thank you

$$\%error = 100 \times\frac{(Y_{cl}\space when\space w=0)-(Y_{cl}\space when\space w\neq0)}{(Y_{cl}\space when\space w=0)}$$
Note that $(Y_{cl}\space when\space w=0) = \frac{100}{101}\times r$