Answer
$2500$ dollars at $4\%$, $6500$ dollars at $7\%$.
Work Step by Step
Step 1. Assume the investment for the $4\%$ account is $x$ dollars. Then the amount left for the $7\%$ account is $9000-x$.
Step 2. The total interest is given by $0.04x+0.07(9000-x)=555$, $0.04x+630-0.07x=555$ and $0.03x=75$, which gives $x=2500$
Step 3. The investment for the $4\%$ account is $2500$ dollars and the investment for the $7\%$ account is $6500$ dollars.
