What is the relationship between relative mass and molar mass?

[Lim Y K]

Molar mass is the mass of one mole of atoms of the element .

Relative mass is average mass of one atom of that element compared to 1/12 of mass of one carbon-12 atom

I don't understand how they are equal. Can someone explain to me please?

 

[Borek]

We defined mole in such a way it works.