So far the business has only made one model: the Westminster Abbey. Direct materials for this model cost 60p, direct labour 30p, packaging 15p per unit and it sells for £2.30. It has now been suggested that they could also make a model of Windsor Castle. Direct materials for Windsor Castle will cost 90p, direct labour 35p and packaging 20p per unit and it will have a selling price of £3.00. The fixed costs of £850 per week would be unchanged by this proposal. Construct a marginal cost statement showing the marginal cost for 1 unit of each model and rank the two products according to the contribution per unit.