Cullumber Windows manufactures and sells custom storm windows for three$-$season porches. Cullumber also provides installation

service for the windows. The installation process does not involve changes in the windows, so this service can be performed by other

vendors. Cullumber enters into the following contract on July $1,2025,$ with a local homeowner. The customer purchases windows for

a price of $$2,490$ and chooses Cullumber to do the installation. Cullumber charges the same price for the windows irrespective of

whether it does the installation or not. The customer pays Cullumber $$1,936($which equals the standalone selling price of the

windows, which have a cost of $$1,110)$ upon delivery and the remaining balance upon installation of the windows. The windows are

delivered on September $1,2025,$ Cullumber completes installation on October $15,2025,$ and the customer pays the balance due.