SOLUTION: Need help setting this up: A couple invested part of $12,000 at 6% interest, and the rest at 7.5%. If their target annual income os $810, how much money should they invest in each

Algebra ->  Customizable Word Problem Solvers  -> Finance -> SOLUTION: Need help setting this up: A couple invested part of $12,000 at 6% interest, and the rest at 7.5%. If their target annual income os $810, how much money should they invest in each      Log On

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Question 884939: Need help setting this up:
A couple invested part of $12,000 at 6% interest, and the rest at 7.5%. If their target annual income os $810, how much money should they invest in each account?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +x+ = amount invested @ 6%
+12000+-+x+ = amount invested @ 7.5%
-------------------
+.06x+%2B+.075%2A%28+12000+-+x+%29+=+810+
+.06x+%2B+900+-+.075x+=+810+
+-.015x+=+-90+
+x+=+6000+
+12000+-+6000+=+6000+
-------------------------
They need to invest half of the $12,000
at each rate
-----------
check:
+.06x+%2B+.075%2A%28+12000+-+x+%29+=+810+
+.06%2A6000+%2B+.075%2A6000+=+810+
+360+%2B+450+=+810+
+810+=+810+
OK