When Truck Rent-A-Center re-rents the trucks for the same price, it gains as much rent on the new contract as it loses on the Puritan contract. It may have taken a few days to establish the new contract -- and, if so, it would be entitled to that few days' rent as damages from Puritan -- and Truck Rent-A-Center may have incurred costs in negotiating the new contract with the other delivery company.
Apart from these relatively minor costs, however, the breach does not really damage Truck Rent-A-Center.
This outcome is illustrated on the following page.