Given data:
The expression for the total amount iis x+y=4000.
The total investment is 340.
The expression for the total investment is,
[tex]0.1x+0.06y=340[/tex]Substitute (4000-x) for y in the above expression.
[tex]\begin{gathered} 0.1x+0.06(4000-x)=340 \\ 0.1x+240-0.06x=340 \\ 0.04x=100 \\ x=2500 \end{gathered}[/tex]The value of y is,
[tex]\begin{gathered} y=4000-2500 \\ =1500 \end{gathered}[/tex]Thus, the system of equations that define the situation are x+y=4000, and 0.1x+0.06y=340. The amount Lisa invested in 10% rate is $2500, and the amount Lisa invested in 6% rate is $1500.