Which is bigger two thirds or four fifths?

At his new job, jeremiah can choose an hourly rate of $9 plus a $50 weekly bonus for opening the store, or an hourly rate of $10 per hour with no opening bonus. the equations model his salary options. y = 9x + 50 y = 10x

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

Can someone answer this question? : )