Find the length of bc.

a) 8
b) 12
c) 16
d) 18

B

6/4=18/X
6x= 72
X=12

Or you can say 4+4+4=12

Mean is the average. To find the average of any set of numbers, you add up the numbers and divide that sum by the number of numbers you added.  Here when you add the numbers together you get 365. Because there were 10 numbers there, divide 365 by 10 to get 36.5, or B