A parking lot is to be constructed for x lorries and y buses. Lorries are allowed 10 square metres of space and buses 20 square metres of space and there is only 500 square metres available. All vehicles are allowed to park and at most 16 buses are allowed. Not more than 42 vehicles are allowed at a time. The parking charge for a lorry is Shs. 5000 and for a bus Shs. 20000. write down all the inequalities to represent the given information.