Question 125515
Invested $22,000, part at 8% and part at 7%. If the total interest at the end of the year is $1,710, how much did she invest at 8%? 
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I'll do one and leave the other to you.
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Let amt invested at 8% be "x" ; interest is 0.08x dollars
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Amt invest at 7% is "22000-x ; interest is 0.07(22000-x) = 1540-0.07x dollars
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EQUATION:
interest + interest = 1710 dollars
0.08x + 1540-0.07x = 1710
0.01x = 170
x = $17000 (amt. invested at 8%)
22000-x = 5000 (amt invested at 7%)
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Cheers,
Stan H.