At the gas station the equation c=2.80g gives the relationship

Step-by-step explanation:

Let

g ----> number of gallons of gasoline

c ---> the total cost in dollars

we have

First gas station

This is a proportional relationship between the variables c and g

The constant of proportionality k or unit rate (slope) is equal to

Second gas station

we have the ordered pairs

(2.5,8.30) and (5,16.60)

This is a proportional relationship between the variables c and g

The constant of proportionality k is equal to

the linear equation is

To find out how much per gallon would Billy save, subtract the unit rate of the Gas station 1 from the unit rate of the Gas station 2

so

addition

step-by-step explanation:

they charge the same amount at 20 minutes.

step-by-step explanation: