Question

$8,000 is invested in two different accounts earning 3% and 4% interest. If the two accounts earn a total of $295 in interest, how much money was invested at 3%?

Answer 1

The money invested at `3%` is $`2500`.

Explanation:

We call the quantity invested at `3%` as `X` and the quantity invested at `4%` as `Y`.

Than we have that $$X+Y=8000$$ and also $$X\times 3/100+Y\times4/100=295.$$

We are interested in `X` so from the first equation we have `Y=8000-X` and we substitute in the second equation

$$X\times 3/100+(8000-X)\times4/100=295$$
and we solve for `X`
$$3X-4X+32000=29500$$
$$-X=29500-32000$$
$$X=2500.$$