A matatu , which has a capacity of 14 passengers charges sh. 100 as fare from Nairobi to limuru which are 35 km apart. it can however carry 2 more passengers but at a penalty of sh. 50 at each of the 5 checkpoints. If the matatu consumes 1 litre of petrol for every 5 km , calculate a)how much is gained if the matatu does not overload

b) how much is lost if the matatu overloads. ( Take the price of 1 litre of petrol to be sh. 85)