Question 43727
Hello!

This can be solved with a system of 3 equations and 3 unknowns. Let's call X to the amount invested at 5%, Y to the amount invested at 8% and Z to the amount invested at 12%.
Since she has $45,000, we have:

{{{X + Y + Z = 45000}}}

We also know that "Melody wants to have the amount invested at 12% to be double the amounted invested at 8%". Therefore,

{{{Z = 2Y}}}

Finally, she "wishes to receive an annual income of $4290 from this money". Therefore, we get:

{{{0.05X + 0.08Y + 0.12Z = 4290}}}

So we have the system:
{{{system(X + Y + Z = 45000,Z = 2Y,0.05X + 0.08Y + 0.12Z = 4290)}}}


This system can be solved with any method you prefer (for example, by substitution). The solutions are:
X=9000
Y=12000
Z=24000

Therefore, she should invest $9,000 at 5%, $12,000 at 8% and $24,000 at 12%


I hope this helps!
Get more answers at <a href=http://www.onlinemathanswers.com>Online Math Answers.com</a>!