Correct. Using the formula $\displaystyle{r}=\frac{{W}}{{t}}\usepackage{cmbright}\Huge\$ , you related the rates of the individual machines ( $\displaystyle\frac{{20}}{{{2.5}}}\usepackage{cmbright}\Huge\$ and $\displaystyle\frac{{{10}}}{{1}}\usepackage{cmbright}\Huge\$ ) with the total rate of production.