I need the steps to this equation.?

I need the steps to this equation.?

A person invested $6400 for 1 year, part at 5%, part at 10%, and the remainder at 13% was $687. The amount of money invested at 13% was $400 more than the amounts invested at 5% and 10% combined. Find the amount invested at each rate.

Question

I need the steps to this equation.?

I need the steps to this equation.?
 
A person invested $6400 for 1 year, part at 5%, part at 10%, and the remainder at 13% was $687. The amount of money invested at 13% was $400 more than the amounts invested at 5% and 10% combined. Find the amount invested at each rate.

pfenn1 · Answer

Let x = $ invested at 5%
y = $ invested at 10%
686 = $ invested at 13%
We know that 6400 was invested so $$x+y+686=6400$$We also know that $687 is $400 more than the amounts invested at 5% and 10% combined, or$$687-400=x+y$$So now we have two equations and two unknowns.  Can you solve this?