Answer :
[tex]\begin{gathered} I=\frac{prt}{100} \\ \end{gathered}[/tex]
total interest = $520
Therefore,
let
x = amount invested in 6%
y = amount invested in 10%
[tex]\begin{gathered} x+y=7000 \\ y=7000-x \end{gathered}[/tex]Interest total
[tex]\begin{gathered} 520=\frac{x\times6\times1}{100}+\frac{y\times10\times1}{100} \\ 520=0.06x+0.1y \end{gathered}[/tex][tex]\begin{gathered} 520=0.06x+0.1(7000-x) \\ 520=0.06x+700-0.1x \\ 520-700=0.06x-0.1x \\ -180=-0.04x \\ x=\frac{-180}{-0.04} \\ x=\text{ \$4500} \end{gathered}[/tex]y = 7000 - 4500 = $2500
$4500 was invested at a 6% rate
$2500 was invested at a 10% rate