I always trip on this one. I just can't wrap my head around how manĝo can be one meal while manĝaĵo can be food in general when it contains the aĵ affix which is supposed to mean a concrete, specific instance. It seems completely upside down to me.
Ne, vi ne malpravas. Manĝaĵo estas tio, kio povas esti manĝata. Manĝo estas ago manĝi. In English: Food is that, which can be eaten. A meal is the act of eating. Anything that can be eaten is food (manĝaĵo)
My translation: No one's meal is ready was faulted which is a correct translation. However, the solution incorrectly shows: No ones's meal is ready. Please amend.