Question 1025200
Call what she invests at 4%, x.  Thus she invested 9000-x at 7%.  The setup then looks like this:
.04x + .07(9000-x) = 540
Now solve for x...
.04x + 630 - .07x = 540
-.03x = -90
x = $3000 at 4%  and thus
9000-x = $6000 at 7%