The equivalent unit rate for 15 miles per gallon is 60 miles per 4 gallons () , this answer mentioned in the option D.
Step-by-step explanation:
     The given is,
         15 miles per gallon
Step:1
     From given, the rate is
             = 15 miles per gallon
             = = 15 miles.........................(1)
Step:2
     Check for Option A,
              = 30 miles per 3 gallons
              = = 10 miles.....................(2)
     From the eqn (1) and (2),
                 Eqn (1) ≠Eqn (2)
Step:3
      Check for Option B and C are not match with given because, Miles provided first or top then the gallons provided the last or bottom.
Step:4
     Check for Option  D,
              = 60 miles per 4 gallons
              = = 15 miles.........................(3)
      From the eqn (1) and (3),
               Eqn (1) ≠Eqn (3)
Result:
     The equivalent unit rate for 15 miles per gallon is 60 miles per 4 gallons () .
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