Question 901861
A man invested half of his money at 5%, one-third of his money at 4%, and the rest of his money at 4.5%. If his total annual investment income was $550, how much had he invested? 
***
let x=total amount invested
x/2=amt invested at 5%
x/3=amt invested at 4%
x-(x/2+x/3)=x-3x/6-2x/6=x/6=remaining amt invested at 4.5%
..
5%(x/2)+4%(x/3)+4.5%(x/6)=550
lcd:6
.05*3x+.04*2x+.045*x=3300
.15x+.08x+.045x=3300
x=12000
how much had he invested? $12,000