If I'm given the applied force of an object, normal force and acceleration how do I find mass

Force = (mass) x (acceleration)Mass = (force) / (acceleration)The mass of the object is . . .       (force in the direction of acceleration) / (acceleration in that direction) .If the normal force isn't in the direction of motion, then it isn't involved in the acceleration, and it can be ignored.  (In more-complicated problems, the normal force might produce a friction force along the direction of motion, and that would get involved with the applied force.)