I don't know if you still need help. but the answer is the first one.
Answer:
The guard should be positioned at the safe
Step-by-step explanation:
The night watchmen should be positioned to guard whichever place gives the highest expected value to the thief.
The expected value of robbing the safe is:

The expected value of robbing the cash register is:

Therefore, the guard should be positioned at the safe since it yields a higher expected value to the thief in case he tries to rob it.
Answer:
63 vehicles are not white
Step-by-step explanation:
Well you know that there are 175 total vehicles, and that 64% of those vehicles are white. Therefore the remaining percentage of vehicles must not be white.
100%-64%=36%
This means that 36% of the vehicles aren't white.
Now you must find what 36% of 175 is. The word "of" always signals for multiplication, which is exactly what you need to do here. First start by converting the percentage into decimal form:
36%=0.36
Now you can multiply
175 x 0.36 = 63
63 Vehicles are not white