Question 671779
5.5% ------------ investment x
7%--------------- investment x+250

Total interest = 800

5.5%x+7%(x+250)=800

multiply by 100
5.5x+7(x+250)=800*100
5.5x+7x+1750=80000
12.5x=80000-1750
12.5x=78250
x=6260

$6260 @ 5.5%
$6510  @7%