A roofer agrees to put a new roof on a gift shop by 1 December for a price of $3,000. The shop owner explains that in the run up to Christmas last year the shop made a profit of $300 per day. The roofer therefore agrees that in the event of his not performing the contract on time he will pay $300 damages for every day that he is late. Both of the roofer's employees leave. The roofer does his best but cannot finish the job until 6 December. The shopkeeper admits that trade in the area has been well down on last year and that this year the shop would only have made $150 profit per day. Which one of the following statements is true