SOLUTION: Here's my question: 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%? I got $11,000, but I d

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: Here's my question: 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%? I got $11,000, but I d      Log On

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Question 121765: Here's my question: 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%? I got $11,000, but I don't think that's right.
Answer by oscargut(2103) About Me  (Show Source):
You can put this solution on YOUR website!
C1 +C2 = 20000
C1(0,14)+C2(0,13)=2720
then
(0,14)C1+(0,14)C2=2800
-(0,14)C1-(0,13)C2=-2720
(0,01)C2=80 then C2=8000 and C1=12000