SOLUTION: Carla invested $28,000, part at 14% and part at 9%. If the total interest at the end of the year is $3,370, how much did she invest at 14%?

Algebra ->  Customizable Word Problem Solvers  -> Finance -> SOLUTION: Carla invested $28,000, part at 14% and part at 9%. If the total interest at the end of the year is $3,370, how much did she invest at 14%?      Log On

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Question 105784: Carla invested $28,000, part at 14% and part at 9%. If the total interest at the end of the year is $3,370, how much did she invest at 14%?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
F-amount invested at 14%
N-amount invested at 9%
Total amount = F + N = $28000
1.F%2BN=28000
Interest at 14% plus Interest at 9% = Total interest = $3370.
2.0.14%2AF%2B0.09%2AN=3370
Use equation 1. to solve for F in terms of N,
1.F%2BN=28000
F=28000-N
Substitute your result into equation 2.
2.0.14%2AF%2B0.09%2AN=3370
0.14%2A%2828000-N%29%2B0.09%2AN=3370
0.14%2A%2828000%29-0.14N%2B0.09%2AN=3370
3920-0.05%2AN=3370
-0.05%2AN=3370-3920
-0.05%2AN=-550
N=%28-550%29%2F%28-0.05%29
highlight%28N=11000%29
F=28000-N
F=28000-11000
highlight%28F=17000%29
Check your answer.
1.F%2BN=28000
17000%2B11000=280000
28000=28000
Good answer.
2.0.14%2AF%2B0.09%2AN=3370
0.14%2A17000%2B0.09%2A11000=3370
2380%2B990=3370
3370=3370
Good answer.
$17,000 at 14% and $11,000 at 9%.