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

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

eventually after a few more steps, your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x