Mr. Smith invests a certain amount of money at 8% and twice as much at 5%. If his annual income from the two investments is $720, how much does he have invested at 5%? (in $)

Guest Mar 10, 2020

#1**+1 **

Let the amount of money Mr. Smith invested at \(8\)% be \(m\). This makes the amount of money Mr. Smith invested at \(5\)% equal to \(2m\).

Now we can create an equation:

\($0.08m + 0.05 \cdot $2m = $720\)

Simplifying the equation:

\(0.05 \cdot $2m = $0.1m\).

And the simplified equation:

\($0.08m + $0.1m = $720\)

Adding like terms:

\($0.18m = $720\)

Solving for \(m\):

\({0.18m \over 18} = {720 \over 18}\)

\(0.01m = $40\)

\(0.01m \cdot 100 = 40 \cdot 100\)

\(m = 4000\)

Mr. Smith invested \($4000\) at \(8\)%, so he invested \($8000\) at \(5\)%.

**ANSWER: **\($8000\).

I hope this is helpful,

Catarina

Catarina Mar 10, 2020