I'm trying to compile this program and it gives me the following errors:

mp.obj : error LNK2001: unresolved external symbol "public: void __thiscall Fraction::reduce(int,int)" (?reduce@Fraction@@QAEXHH@Z)

imp.obj : error LNK2001: unresolved external symbol "public: struct fraction __thiscall Fraction:ivide(struct fraction,struct fraction)" (?Divide@Fraction@@QAE?AUfraction@@U2@0@Z)

imp.obj : error LNK2001: unresolved external symbol "public: struct fraction __thiscall Fraction::Multiply(struct fraction,struct fraction)" (?Multiply@Fraction@@QAE?AUfraction@@U2@0@Z)

imp.obj : error LNK2001: unresolved external symbol "public: struct fraction __thiscall Fraction::Subtract(struct fraction,struct fraction)" (?Subtract@Fraction@@QAE?AUfraction@@U2@0@Z)

imp.obj : error LNK2001: unresolved external symbol "public: struct fraction __thiscall Fraction::Add(struct fraction,struct fraction)" (?Add@Fraction@@QAE?AUfraction@@U2@0@Z)

Debug/Fraction.exe : fatal error LNK1120: 5 unresolved externals

Error executing link.exe.

Can someone tell me what they mean?