SOLUTION: Bob invested $20,000, part at 14% and part at 13%. If the total interest at the end of the year is $2,720, how much did he invest at 14%?

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Question 54711: Bob invested $20,000, part at 14% and part at 13%. If the total interest at the end of the year is $2,720, how much did he invest at 14%?
Answer by tutorcecilia(2152) About Me  (Show Source):
You can put this solution on YOUR website!
Ax+By=C [Use the standard equation of a line]
(14%)(x)+(12%)($20,000-x)=$2,720
.14x+.12(20,000-x)=2720
.14x+2400-.12x=2720 [Solve for x]
.14x-.12x=2720-2400
.02x=320
x=$16,000
.
14%of $16,000 = (.14)(16,000)=$2,240
12% of ($20,000-$16,000)=.12(20,000-16,000)=$480
So, $2,240+$480=$2,720