Ok I know how to do this but what do I need to do?
Because the fence's dimensions is 30 feet by 10 feet, you can assume that one side of the pool is 30 feet while the other, non-congruent side, is 10 feet. The formula for perimeter, which you are trying to find, is 2L+2W=P. In this problem, 30 will be your L and 10 will be your W. Therefore, 2(30) +2(10)=80.
So 80 feet will be your answer.
Answer:
a)
ways
b)
ways
c)
ways
Step-by-step explanation:
Combinatory means combination or arrangement of different elements.
If we have n total elements and we want to find in how many ways we can select x we can use this general formula:

Where 
a. How many different ways can four pieces be selected from the 12 colored pieces?
For this case we have:
ways
b. How many different ways can two orange pieces be selected from five orange pieces?
For this case we have:
ways
c. How many different ways can two brown pieces be selected from seven brown pieces?
For this case we have:
ways
Answer:
b. 4+7x-2
Explanation:
when you add like terms for the first equation it becomes 7x-6
the second one becomes 7x+2
the third one becomes 7x-6
and the last one is also 7x-6
which means the second one is not equivalent