Most of Conservative Casey's money was put into a savings account that paid 5% interest a year, but some of it was put into a risky stock fund that paid 16% a year. Casey's total initial investment in the two accounts was $10000. At the end of the first year, Casey received a total of $775 in interest from the two accounts. Find the amount invested in each.
+36916 x = money at 5% interest
10000 -x = money at 16%
.05 x + .16 ( 10000 - x ) = 775
x = 7500 at 5% then 2500 at 16 %
