It can't they have no common factor
To find your new number of sales per month, you will need to find the number of sales you have per month (based on 30 days per month).
55 x 20 = 1650 sales.
Than, you will need to calculate what 10% of this is and add it to your original sales number.
0.1 (10%) x 1650 = 165
1650 + 165 = 1815
You will need approximately 1815 sales based on the 30 day month.
V = Bh ⇒
h = V/B = 1122 / 93.5 = 12 inches.
You need to set up a linear graph. One side with gallons and the other with dollars. Point 1 will be at (1500, 2.10). Point 2 (1300, 2.95). Draw a straight line through these points in your graph and your graph will then give you the answers to your other questions.