Instantaneous rate
$=-\frac{1}{\mathrm{a}} \frac{\mathrm{~d}[\mathrm{~A}]}{\mathrm{dt}}=-\frac{1}{\mathrm{~b}} \frac{\mathrm{~d}[\mathrm{~B}]}{\mathrm{dt}}=\frac{1 \mathrm{~d}[\mathrm{C}]}{\mathrm{c}} \frac{1}{\mathrm{dt}}=\frac{\mathrm{d}[\mathrm{D}]}{\mathrm{d}} \frac{\mathrm{dt}}{}$
$\therefore \quad$ The reaction can be represented as
$\mathrm{aA}+\mathrm{bB} \rightarrow \mathrm{cC}+\mathrm{dD}$