Question 972166
x=4% investment amount
15000-x= 5%  investment amount

690=.04x + .05 (15000-x)    since the interest earned is the principal *rate* time, which is one year, or 1

690=0.04x+ 750-.05x
-60=0.01x
multiply by (-100)

$6000=x  That makes $240 at 4%
$9000=15000-x.  That makes $450 at 5%   ;  total interest is 690.  Checks.