Question 945410
Let the amount you invest at 4.5% be x. Then the amount invested at 3% is {{{25000-x}}}

You are told 
{{{(x* 0.045) + ((25000-x)*0.03) = 9000}}}
Solve for x

{{{0.045x + 750 - 0.03x = 9000}}}
{{{0.015x = 8250}}}
{{{x = 8250/(0.015)}}}

Solving for x gives a number greater than 25000. So the answer is "you can't do that".

To verify that, imagine you invested the entire 25000 at the higher rate of 4.5%. How much will that return in a simple interest year? $1125 which is nowhere near 9000.

Did you have a typo maybe?? Perhaps 900??