Answer:
Mean
Step-by-step explanation:
Given

Required
Best measure of center
The mean is considered the best measure of center when there are no outliers in the given data.
Outlier is when a particular data set is far away from other datasets.
For instance: 20 is an outlier in the following data sets: 
Also, the given data are not open-ended.
An open-ended data is as follows: 
Since we do not have any of the above conditions, then the mean is the best center to use.
Answer:
21
Step-by-step explanation:
Distribute 5/7 through the parentheses and add like terms after.
Answer: 11/7x + 11/35y
Answer:
2 x y^2 (x y - 1) (x y - 3)
Step-by-step explanation:
2x^3y^4-8x^2y^3+6xy^2
each term contains 2xy^2 so factor that out
2xy^2(x^2y^2 -4xy+3)
then lets factor the inside
what terms multiply together to give us +3 and add to -4
-3* -1 = 3 -3+-1 =-4
2 x y^2 (x y - 1) (x y - 3)