SOLUTION: Sam invested his savings in two investment funds. The amount he invested in Fund A was $8000 less than the amount he invested in Fund B. Fund A returned a 5% profit and Fund B retu

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Question 908963: Sam invested his savings in two investment funds. The amount he invested in Fund A was $8000 less than the amount he invested in Fund B. Fund A returned a 5% profit and Fund B returned a 3% profit. How much did he invest in Fund B, if the total profit from the two funds together was $640?
Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
We don't know the total invested.
We know the difference in the two accounts.
We know that the interest for the two accounts is $640
0.03*x+0.05*y=640
We know that the account at 3% has $8000 more.
x=8000+y
We substitute for x
0.03*(8000+y)+0.05*y=640
We multiply out
240+0.03y+0.05*y=640
We combine like terms.
0.08*y=400
Isolate y
y=$5000 at 5%
x=8000+y
Calculate x
x=$13000 at 3%
Now,we know the total invested is: 18000
Total invested $13000+$5000=$18000
We check
0.03*13000+0.05*5000=640
390+250=640
640=640
Since this statement is TRUE and neither x nor y is negative all is well.