Acar wash machine cleaned 20 cars in 50 minuets at this rate how many minutes will it take the machine to clean 1 car

For this case what we should do is define variables:
 x: time in minutes
 y: number of clean cars
 We then have the following equation:
 y = (20/50) x
 For 1 car we have:
 1 = (20/50) x
 Clearing x:
 x = 50/20
 x = 2.5 minutes
 
 It will take the machine to clean 1 car about:
 x = 2.5 minutes