I am not sure how to show you how to do a dot plot on this website, but to see how to do a dot plot
b) Put everything in order and find the middle
10, 10, 10, 20, 30, 30, 30, 30, 40, 50, 50, 50, 60, 60, 70, 70, 2040
^^
So 40 is in the middle, making it the median
c) Add all of the values together and divide by the total number of values.
10 + 10 + 10 + 20 + 30 + 30 + 30 + 30 + 40 + 50 + 50 + 50 + 60 + 60 + 70 + 70 + 2040 = 2660
2660 / 17 = 156.5
I'm assuming this is a system of equations you want solved so,
x = -y + 3
-2(-y+3)+4y = 6
2y - 6 + 4y = 6
6y = 12
y = 2
x + 2 = 3
x = -1
(-1,2)
V=πr^2h/3=π·3^2·11.5/3≈108.38495 or 108.40 rounded