It is believed that this phrase wasinvented in the 1870s during slavery inthe southern states of America. As part ofa dance or celebration organized by slaveowners, black slaves would compete incake walksperforming a dance whichimitated and subtly mocked the elaborateand ostentatious gestures of the whiteslave owners. The most elegantcouple/team would be given a cake as anaward. It seems that the white slaveowners didn't understand that they werebeing mocked in these elaborate cakewalkdances, and took great delight inwatching their slavesemulating their refined behavior. The piece of cake that was awarded as the prize to the best couple/team, came to be known among the blacks as something very easy to obtain.
[ Examples ]
1. Don't worry, Sophie. This job interview will be a piece of cake for you. You have all the skills they need and I think you're absolutely the best candidate. 2. They said the test would be difficult, but it was a piece of cake. I'll pass with no problem at all. 3. Don't think that this term's work will be a piece of cake. You'll have to study hard to get good grades.