I might not be understanding what you mean but I think it is by counting 10s. 170,180,190,200,210,220,230,240,250,260,270,280,290,300,310,320,330,410.
No, line graphs are used only to show change over time
Answer: 
Step-by-step explanation:
The missing figure is attached.
The volume of an oblique cylinders and the volume of a right cylinder can be found with this formula:
Where "r" is the radius and "h" is the height.
The volume of an oblique cone and the volume of a right cone can be found with this formula:
Where "r" is the radius and "h" is the height.
According to the information given in the exercise, you know that the volume of the cylinder and also the radius of the cylinder and the cone ,are the following:

Therefore, in order to find the volume of the cone, you only need to multiply the volume of the cylinder by
.
Then, you get:

Total amount paid if he bought = 6000 + 726(12 x 3) = 6000 + 726(36) = 6000 + 26,136 = 32,136
Total amount paid if he rents = 2000 + 37P, where P is the monthly rent
For renting to be cheaper
2000 + 37P < 32,136
37P < 32136 - 2000 = 30136
P < 30136 / 37 = 814.49
Therefore, the maximum rent he could pay is $814