SOLUTION: Donna invested her 33000 bonus, and received a total of 970 in interest after one year. If part of the money returned 4% and the remainding 2.25%. then how much did she invest at e

Algebra ->  Linear-equations -> SOLUTION: Donna invested her 33000 bonus, and received a total of 970 in interest after one year. If part of the money returned 4% and the remainding 2.25%. then how much did she invest at e      Log On


   



Question 198412: Donna invested her 33000 bonus, and received a total of 970 in interest after one year. If part of the money returned 4% and the remainding 2.25%. then how much did she invest at each rate?
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let a= amount invested @ 4%
Let b= amount invested @ 2.25%
.04a+%2B+.0225b+=+970
Multiply both sides by 10000
(1) 400a+%2B+225b+=+9700000
a+%2B+b+=+33000
Multiply both sides by 225
(2) 225a+%2B+225b+=+7425000
Subtract (2) from (1)
(1) 400a+%2B+225b+=+9700000
(2) -225a+-+225b+=+-7425000
175a+=+2275000
a+=+13000
And, since
a+%2B+b+=+33000
13000+%2B+b+=+33000
b+=+20000
She invested $13,000 @ 4% and $20,000 @ 2.25%
check:
.04a+%2B+.0225b+=+970
.04%2A13000+%2B+.0225%2A20000+=+970
520+%2B+450+=+970
970+=+970
OK