Question #b72fe

Question

1053 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2017-10-03T14:25:04

I got: $6000 and 4000$ Euros

Let us call the two quantities (at $8% and 9%$ ) $x and y$ , we get:

$x+y=10000$
$0.08x+0.09y=840$

Let us solve using the first equation rearranged:

$x=10000-y$

into the second:

$0.08(10000-y)+0.09y=840$

$800-0.08y+0.09y=840$

$0.01y=40$

$y=40/0.01=4000$ Euros

so that:

$x=10000-4000=6000$ Euros

Answer 2 · 2017-10-06T23:10:00

Elimination Method: $y=4000$ euros

Another way to attack it. Using Gio's equations:

$x+y=10000$
$0.08x+0.09y=840$

Since we are looking for $y$ which is how much was invested at $9$ %, let's eliminate $x$ .

We can do that by multiplying the top equation by $0.08$ and then subtracting the two equations:

$0.08x+0.08y=800$
$0.08x+0.09y=840$

$-0.01y=-40$

$y=4000$ euros