Question 325989
let him invest $ x at 10%
so 12000-x will be invested at 9%
interest earned on both =$1130
..
0.1x+0.09(12000-x)=1130
0.1x+1080-0.09x=1130
0.01x=1130-1080
0.01x=50
x=50/0.01
x= 5000 
$5000 invested @10%
$7000 invested @9%