Answer:
4
Step-by-step explanation:
We need to find the factors of each number
28 -
1x28
2x14
4x7
60 -
1x60
2x30
3x20
4x15
5x12
6x10
then we need to find the largest number they have in common
in this case it is 4
Answer:
4y
Step-by-step explanation:
Answer:
Third option. 
Step-by-step explanation:
For this exercise you need to remember one of the properties for exponents.
There is a property called the "Negative property of exponents" which states the following:
Where 
As you can observe,
is the reciprocal of 
In this case you have the following expression given in the exercise:

Observe the expression. As you can notice, the base "n" has a negative exponent, which is -6.
Therefore, applying the Negative property of exponents explained at the beginning of this explanation, you can simplify the expression.
Then, the simplified form of
is the one shown below:
