The trick it to separate the 7/10 relating to the x-coordinates from the 7/10 relating to the y-coordinates.
For the x-coordinate:
You need to find the difference in the x-values
12-(-4) = 16
and then find 7/10 of that and add it to the starting x-coordinate (the x-coordinate of Point A).
For the y-coordinate:
You need to find the difference in the y-values
4-(-5) = 9
and then find 7/10 of that and add it to the starting y-coordinate (the y-coordinate of Point A).
Can you take it from there?