Answer: 14 kg
Step-by-step explanation:
First, we need to find the force applied to the objects. We can find this with the mass and the acceleration of the first object using the formula F=ma.
F = 6*7 = 42 N.
Since the same force acts upon the other object, we can use the same formula F=ma to solve for the mass of the other object.
42 = m*3
m = 14 kg