PLS HELP ME WITH THIS

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?

Mackinzie walks 4 blocks west, then 2 blocks south, then 4 blocks east, and,finally, 1 block south. what is the magnitude of her total displacement duringthis walk (in blocks)?

A15 ohm resistor and a 25 ohm resistor are connected in a series to a 60 volt battery. what is the power used by each device