This can be obtained by following the Newton's Second Law of motion. It states that the acceleration of an object which is produced by a net force is directly related to the net force and inversely related to the mass of the object. We use the equation:
a = F/m
10 = F/2 / 2m
10 = F/4m
40 = F/m
So, the acceleration of the system is 4 times the original conditions.