On the first part of a journey, Alan drove a distance of x km and his car used 6 litres of fuel. The rate of fuel used by his car was litres per 100 km. 600/x
a) Alan then drove another (x+20) km and his car used another 6 litres of fuel.
(i) Write down an expression, in terms of x, for the rate of fuel used by his car on this part of the journey. Give your answer in litres per 100 km.
(ii) On this part of the journey the rate of fuel used by the car decreased by 1.5 litres per 100 km.