Here you have two sets of parentheses. Order of operations rules (PEMDAS) require that you perform any operations that are presented within parentheses first. Mult and div come next, and then any addition and/or subtraction.
We must perform the addition 4+8 first; the correct outcome is 12. Then we have:
16 • [(12)÷4]
We must perform the operation inside brackets first:
16*[3] = 48 (answer)