`mpg = float(input('Enter miles per gallon:'))
 gp = float(input('Enter the gas price:'))
 price = (10*1.0/mpg)*gp print(price) 
 price = (50*1.0/mpg)*gp print(price) 
 price = (400*1.0/mpg)*gp print(price)`      

这就是答案，已解决