An object is found to move with an acceleration of magnitude 6 m/s2 when it is subjected to a force of magnitude 214 N. How do I find the mass of the object?

Use Newton's Second Law of Motion (http://en.wikipedia.org/wiki/Newton%27s_laws_of_motion).

Thanks a lot it worked

The basic formula that you have to know is F=ma.

F : Force applied
m: mass
a: acceleration in the direction of that force.

first you substitue the numbers.
use newtons second law "Force equals Mass times Acceleration"
F=MA
Newton=214
Acceleration=6m/s2
214N=m*6m/s2 (divide by 6 on both side)
35.67g (answer)