Produce a decision table to model the logic in this scenario: A postal delivery company delivers parcels air or rail transport. The price of delivery by air depends upon the weight of the parcel. There is a basic charge of £5 per kg up to 50 kg. Excess weight over 50 kg is charged at £3 per kilo. Delivery by rail is charged at £3 per kg up to 50 kg and then £2 per kg. There is a special service guaranteeing same day delivery which carries an additional flat rate charge of £20. Any deliveries overseas are charged at double the normal rate.