In August last year Dino and Maria completed the sale of their 'Venice on a Plate' restaurant in Leichhardt to Luca. Clause 22 of the contract for sale of business stipulated that Dino and Maria could not open or work in 'any restaurant serving any style of Italian food' within 25 kilometres of the Leichhardt shop for a period of 5 years. 3 Before the contract was signed, Maria said to Luca: 'Clause 22 is no good. We only have experience with cooking food. We have to work.' Luca assures them: 'Don't worry. My lawyer put that in. I don't care if you cook southern Italian cuisine. I am only interested in northern Italian food. That is the best food!' Dino and Maria sign the contract. Two weeks ago, a sign went up at empty shop premises in Haberfield approximately one kilometre from Luca's restaurant. The sign said that Dino and Maria would be opening a new restaurant to be named 'Southern Italian Delights' in those premises in three months' time. Dino and Maria seek your advice about the following: a) Whether, and on what basis, Luca could prevent them from opening their new restaurant on the proposed site. (Refer to general law principles and statute) [15 marks] b) Whether Luca's assurance has any legal validity. [10 marks]