Answer
$3000$ dollars in the $6\%$ account and $6000$ dollars in the $7\%$ account.
Work Step by Step
Step 1. Assume $x$ amount is invested in the $6\%$ account and $y$ amount is invested in the $7\%$ account.
Step 2. Based on the conditions given, we get set up the following system of equation:
$\begin{cases} y=2x\\0.06x+0.07y=600 \end{cases}$
Step 3. Use substitution, the second equation becomes $0.06x+0.07\times2x=600$ which gives $x=3000$ and $y=6000$ dollars
Step 4. Conclusion: $3000$ dollars is invested in the $6\%$ account and $6000$ dollars is invested in the $7\%$ account.
