Question 724216
.066X+.041(750,000-X)=15,000
.066X+30,750-.041X=15,000
.025X=15,000-30,750
.025X=-15,750
X=-15,750/.025
X=-630,000 
SOMETHING IS WRONG WITH THIS DATA.
INVESTING ALL THE MONEY @ THE LOWEST RATE (4.1%) YIELDS:
.041*750,000=$30,750