SOLUTION: Helen Weller invested $11,000. Part of it was invested a 5% interest and the rest was invested at 4% interest. How much was invested at each rate if $520 was earned in interest the

Algebra ->  Customizable Word Problem Solvers  -> Finance -> SOLUTION: Helen Weller invested $11,000. Part of it was invested a 5% interest and the rest was invested at 4% interest. How much was invested at each rate if $520 was earned in interest the      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


   



Question 501884: Helen Weller invested $11,000. Part of it was invested a 5% interest and the rest was invested at 4% interest. How much was invested at each rate if $520 was earned in interest the first year?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let a = amount invested @ 5%
Let b = amount invested @ 4%
given:
(1) +a+%2B+b+=+11000+
(2) +.05a+%2B+.04b+=+520+
--------------------
(2) +5a+%2B+4b+=+52000+
Multiply both sides of (1) by 4
and subtract (1) from (2)
(2) +5a+%2B+4b+=+52000+
(1) +-4a+-+4b+=-+44000+
+a+=+8000+
and, since
(1) +a+%2B+b+=+11000+
(1) +8000+%2B+b+=+11000+
(2) +b+=+3000+
$8,000 was invested @ 5% and $3,000 was invested @ 4%
check answer:
(2) +.05a+%2B+.04b+=+520+
(2) +.05%2A8000+%2B+.04%2A3000+=+520+
(2) +400+%2B+120+=+520+
(2) +520+=+520+
OK