the formula for slope is

so just replace y and x for the proper values

enters the irrational number category.
Integers numbers are the numbers without decimals between -infinity and infinity.
Natural numbers are the whole numbers from 1 to infinity.
Whole numbers are natural numbers + 0.
Yes this is a function
The reason why is because the x coordinates do not repeat. Each x value maps to exactly one y value. For any input, there is exactly one output. If you were to graph all of these points, then the graph would pass the vertical line test.
If we had something like (2,4) and (2,0) then the input x = 2 would lead to multiple outputs (y = 4, y = 0) which would not make it a function; however we don't have any repeated x values here.
Answer:
33 gallons
Step-by-step explanation:
44/20 = 2.2
$2.2 per gallon
2.2x15