another wod problem please help.......?

Question

lane invested $14,000, part at 15%, and part at 2%. if the total was $1.060. howmuch did she invest at 15%?

Answer 1

Let's assume that the amount invested in the 15% is a, and the amount invested in the 2% is (14000 - a). The total interest received is $1060, so you can say that 0.15a + 0.02(14000 - a) = 1060 - this just takes the total invested times the interest rate. We can solve this now:

0.15a + 0.02(14000 - a) = 1060
0.15a + 280 - 0.02a = 1060
0.13a = 780
a = 6000

So Lane invested $6000 in the 15% account, and $8000 in the 2% account. To check:

$6000 * 15% = $900
$8000 * 2% = $160
$900 + $160 = $1060 - which is what we said it should be in the problem statement.