Question 168538
lets call x the amount invested at 8% 
and  40000-x the amount invested at 9%
:
those 2 amounts invested multiplied by their perspective interest rates equal the amount of interest made which is 3415

so .08x+.09(40000-x)=3415

.08x+3600-.09x=3415

185=.01x

{{{highlight(x=18500)}}}amount invested at 8%
{{{highlight(40000-18500=21500)}}} amount invested at 9%