Question 563812
An executive invests $10,000,some at 9% and some at 8% annual interest. If he receives an annual return of $830, how much is invested at each rate? 
------------------
Equations:
x  +  y  = 10,000
0.09x + 0.08y = 830
-------------------------
Multiply thru 1st by 9
Multiply thru 2nd by 100
-------------------------
9x  + 9y  = 9*10,000
9x  + 8y  = 83000
----
Subtract and solve for "y":
y = $7000 (amt. invested at 9%)
x = $3000 (amt. invested at 8%
=================================
Cheers,
Stan H.
============