r)(ap)) (rp)) ng formula is a tautology: ((p a) 2. How many elements n E (101, 102,..., 1000} satisfy the following state- ment: 'n is divisible by 5 or by 6 and n is not divisible by 9'? 3. Prove that the relation R defined on the set X = Z by mRn3m + 7n2 is divisible by 10 is an equivalence relation. Determine its equivalence classes [5] R, [2024] R. How many different equivalence classes does this relation have? 4. Let f(n) =3n+5 and g(n) = n be two functi the functions