Try this solution, note a) the suggested way is not the only one, b) the suggested solution is for segments AC:CB=2:1 only.
1) if the point A is (-7;-9), the point B is (5;6) and C is required point, then
2) the coordinate 'x' of the point C is:
[tex]X_C=X_B-\frac{X_B-X_A}{2+1}=5-4=1;[/tex]
3) the coordinate 'y' of the point C is:
[tex]Y_C=Y_B-\frac{Y_B-Y_A}{2+1}=6-5=1;[/tex]
4) the required coordinates are (1;1)
