1
This is the correct answer
Answer: 1/5566
Step-by-step explanation: Try division or simplifying fractions concepts to solve this.
This is how I'd set it up:
405/20 = 243/x
this means the mpg (miles / gallons) for 1 situation is the same as the mpg for the other situation (because the rate is the same)
then just cross multiply and solve:
405x=243*20 or 405x=4860 or x = 12
he would need 12 gallons of gas for 243 miles