since the 5 is a negative you are actually subtracting it from 3
so 3 +(-5) is actually 3-5. which = -2
Your answer is

because the numbers raised to negative powers must be flipped over the divisor to become positive. Then, when multiplying 2 and z, you add their exponents.
91$ per day you divid 455$ by the 5 days and get 91$
It is in the thousandths place