Question

a total of 700 is invested part of 6% and the remainder at 10% how much is invested at each rate if the annual interest is 520

Answer 1

To determine the investment at each rate:

A total of $7000 is invested:

part x at 6% and the remainder 7000-x at 10%. How much is invested at each rate if the annual interest is $520

6% = 6/100 = 0.06

10% = 10/100 = 0.1

`\begin{gathered} 0.06x+0.1(7000-x)=520 \\ 0.06x+700-0.1x=520 \\ 0.06x-0.1x=520-700 \end{gathered}`
`\begin{gathered} -0.04x=-180 \\ \text{divide both side by -0.04} \\ x=-(180)/(-0.04) \\ x=4500 \\ x=\text{ \$4500} \end{gathered}`

x = $4500 -> invested at each 6% rate

while

7000 - x = 7000 - 4500 = $2500 ->invested at each 10% rate

Therefore the invested at each 6% rate = $4500 and invested at each 10% rate = $2500