(no need to show work) create a vector of elements ranging from 1 to 81. Use this vector to create a 9x9 matrix by sequentially filling the columns. That is, the first column should be (1,2,...,9), the second column is (10,11,...,18) and so on. What is the average of the elements of the 6th row less the average of the elements of the 4th column?

-16

10

40

-8

32