It will take 45 weeks.25 weeks to gain back the 500 dollor he spent and 20 to make 400 dollor from it
Negative exponents work like this:

So, in order to evaluate a negative exponent, you simply have to invert the base, and then raise to the positive equivalent of the exponent.
As an example, here are the first three exercises:



You can work out the rest applying this logic.
Answer:
The volume is 
Step-by-step explanation:
From the question ,
and 
The volume of a pyramid is given as

From the question, the base of the pyramid is a square.
Hence base area is given by 
This implies that the volume of the pyramid is




Answer:
Median: 11
Mean: 12
Mode: none
Step-by-step explanation:
M A T H W A Y helps
Mode is something that is repeated multiple times
so