That is very true, but what is the question asking you.
Hello! Assuming that the only force acting on the mass is 30N...
Fnet = 30N
Fnet = ma (mass x acceleration)
ma = 30N
a = 30N / m
a = 30N / 7kg
a = 4.2857 m/s^2
a = 4 m/s^2
I hope this helps!
I’m not sure if this will help but I found: https://prezi.com/l0fa6du3b9kp/going-off-the-grid-assignment/?fallback=1 and
Answer: The FBI used a technique which is called Latent Fingerprint Identification: a silver nitrate solution was used to cause a reaction of the unseen fingerprints perspiration left by the kidnappers all over the ransom notes. The reaction caused the perspiration to turn into silver chloride. This substance is white and it is also visible to the naked eye which means the fingerprints of the perpetrators were easily identifiable.
sorry if this is wrong, i hope i helped