My lecturer must have gone made, he asked us to do a proof of the following problem inpredicate calculus:

Let S be a non empty subset of real Nos bounded from above.

Let A={as:sεS,a>0}.Thenprove Sup(A)=aSup(S)

Inthe proof we must showexplicitlyany quantifier,propositional logic,real Nos axioms,theorems,definitions involved

I don't know if any of you guys understands whats going on here