smc

You are trying to find $\frac{2(0.06x)}{4500}$, where $x$ is the principle for one investment. To find $x$, solve $0.04(4500-x)=0.06x$. $X$ will come out to be $1800$. Then, plug in x into the first equation, $\frac{2(0.06)(1800)}{4500}$, to get $0.048$. Finally, convert that to a percentage and you get $\boxed{4.8\%}$.