Question 40396
Benjamin has $6000 invested in two accounts. One earns *5 interest per year, and the other pays 7.5% interest per year. If his total interest for the year is $472.50, how much is invested at 8%?

Let amount invested at 7.5% be "x" dollars.
Then amount invested at 8% is "6000-x" dollars.

Interest on the 1st investment is 0.075x dollars
Interest on the 2nd investment is 0.08(6000-x)=480-0.08x dollars

EQUATION:
 interest + interest = 472.50 dollars
  0.075x + 480-0.08x = 472.50
Multiply through by 1000 to get:
  75x + 480,000 -80x = 472500
-5x = -7500
  x=$1500 (amount invested at 7.5%)
6000-x-$4500 (amount invested at 8%)
Cheers,
Stan H.