The equation you are looking for is Newton's 2nd law:
The mass is known (10 kg)
and acceleration is the value to find.
Force is in that notation because it is a vector going 9 newtons east and 14 newtons north. To turn that vector into a magnitude that can be worked with, you square both terms, add them up and put them in a square root.
It should look something like this:
You then plug in the force you found and the given mass:
-replaced "right" and "up" with "east" and "north" to remove ambiguity. [right and up is relative to a coordinate-system (x,y)]