Answer:
[tex]\frac{600}{x+20}\text{ litres per 100 km}[/tex]
Step-by-step explanation:
Given,
The number of litres consumed by car in (x+20) km = 6,
So, number of litres consumed by car in 1 km = [tex]\frac{6}{x+20}[/tex],
Now, number of litres consumed by car in 100 km = 100 × litres consumed by car in 1 km
[tex]=100\times \frac{6}{x+20}[/tex]
[tex]=\frac{600}{x+20}[/tex]
Hence, the rate of fuel used by his car would be [tex]\frac{600}{x+20}[/tex] litres per 100 km.