Jodi went 54 miles on 3.5 gallons of gas, and she wants to know how far she can go on 9 gallons of gas. which proportion would be useful to solve the problem?

a)
9
3
=
54
x
eliminate
b)
9
54
=
x
3
c)
54
3.5
=
x
9
d)
54
9
=
3.5
x

C is your answer because of the fact that it sets the proportion needed to answer the question  which the question would be how many miles can she drive on 9 gallons of gas.

so the correct proportion is 54    x
                                            _      _
                                           3.5    9  !  Then your answer would be she can drive about 139 miles if she has 9 gallons of gasoline.     :  )