SOLUTION: Lisa invested $8000, part at 4% and the rest at 5% per year. How much did she invest at each rate if her total return per year on the investments was $380?

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Lisa invested $8000, part at 4% and the rest at 5% per year. How much did she invest at each rate if her total return per year on the investments was $380?      Log On


   

Question 476003: Lisa invested $8000, part at 4% and the rest at 5% per year. How much did she invest at each rate if her total return per year on the investments was $380?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let a = amount invested @ 4% per yr
Let b = amount invested @ 5% per yr
given:
(1) +a+%2B+b+=+8000+
(2) +.04a+%2B+.05b+=+380+
----------------------
(2) +4a+%2B+5b+=+38000+
Multiply both sides of (1) by 4 and subtract from (2)
(2) +4a+%2B+5b+=+38000+
(1) +-4a+-+4b+=+32000+
+b+=+6000+
and
(1) +a+%2B+b+=+8000+
(1) +a+%2B+6000+=+8000+
(1) +a+=+2000+
$2,000 is invested @ 4% per yr
$6,000 is invested @ 5% per yr