I have java code where I have 2 different java files that contain classes I want to use in the main. When I try to compile the main in the command prompt, I keep getting this error, and I do not know how to fix it. I do not know what I am doing wrong

Assign1.java:77: error: cannot find symbol RemovedDomino = OriginalSet.removeDomino(0); ^ symbol: method removeDomino(int) location: variable OriginalSet of type DominoGroup Assign1.java:78: error: cannot find symbol PlayerSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable PlayerSet of type DominoGroup Assign1.java:79: error: cannot find symbol RemovedDomino = OriginalSet.removeDomino(0); ^ symbol: method removeDomino(int) location: variable OriginalSet of type DominoGroup Assign1.java:80: error: cannot find symbol ComputerSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable ComputerSet of type DominoGroup Assign1.java:147: error: cannot find symbol PlayerSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable PlayerSet of type DominoGroup Assign1.java:150: error: cannot find symbol RemovedDomino = PlayerSet.removeDomino(PlayerDomino-1); ^ symbol: method removeDomino(int) location: variable PlayerSet of type DominoGroup Assign1.java:184: error: cannot find symbol GameSet.addDominoFront(RemovedDomino); ^ symbol: method addDominoFront(String) location: variable GameSet of type DominoGroup Assign1.java:202: error: cannot find symbol GameSet.addDominoFront(Swap); ^ symbol: method addDominoFront(String) location: variable GameSet of type DominoGroup Assign1.java:208: error: cannot find symbol PlayerSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable PlayerSet of type DominoGroup Assign1.java:227: error: cannot find symbol GameSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable GameSet of type DominoGroup Assign1.java:246: error: cannot find symbol GameSet.addDominoBack(Swap); ^ symbol: method addDominoBack(String) location: variable GameSet of type DominoGroup Assign1.java:252: error: cannot find symbol PlayerSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable PlayerSet of type DominoGroup Assign1.java:280: error: cannot find symbol GameSet.addDominoFront(RemovedDomino); ^ symbol: method addDominoFront(String) location: variable GameSet of type DominoGroup Assign1.java:283: error: cannot find symbol ComputerSet.removeDomino(j); ^ symbol: method removeDomino(int) location: variable ComputerSet of type DominoGroup Assign1.java:302: error: cannot find symbol GameSet.addDominoFront(Swap); ^ symbol: method addDominoFront(String) location: variable GameSet of type DominoGroup Assign1.java:305: error: cannot find symbol ComputerSet.removeDomino(j); ^ symbol: method removeDomino(int) location: variable ComputerSet of type DominoGroup Assign1.java:329: error: cannot find symbol GameSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable GameSet of type DominoGroup Assign1.java:332: error: cannot find symbol ComputerSet.removeDomino(j); ^ symbol: method removeDomino(int) location: variable ComputerSet of type DominoGroup Assign1.java:352: error: cannot find symbol GameSet.addDominoBack(Swap); ^ symbol: method addDominoBack(String) location: variable GameSet of type DominoGroup Assign1.java:355: error: cannot find symbol ComputerSet.removeDomino(j); ^ symbol: method removeDomino(int) location: variable ComputerSet of type DominoGroup Assign1.java:367: error: cannot find symbol RemovedDomino = OriginalSet.removeDomino(0); ^ symbol: method removeDomino(int) location: variable OriginalSet of type DominoGroup Assign1.java:368: error: cannot find symbol ComputerSet.addDominoBack(RemovedDomino); ^ symbol: method addDominoBack(String) location: variable ComputerSet of type DominoGroup 22 errors