This answer is not correct. Aluminum has 3 outer shell electrons and readily loses these electrons to become a cation with a charge of positive 3. Sulfur has 6 outer shell electrons and tends to gain two electrons to form a sulfide anion with a charge of negative 2. Remember that elements in columns 1,2 and 3 of the periodic table will tend to lose their outer electrons to become cations with inert gas electron configurations. Elements in columns 5,6 and 7 tend to gain enough electrons to become anions with inert gas electron configurations.

You then need to make sure that the combination of the ions will result in no overall charge for the ionic inorganic compound. An easy way to do this is to use the numerical values (not the sign) of the charges of the ions as the subscripts for the other elements.