i believe its 28 because if there are 28 notebooks in packs of 4 and 3 packs are sold then there is 1 more packet left and one packet has 28 notebooks so ya. but the wording is wierd so it might not be the answer
16 because if there are 28 notebooks and they come in packs of 4 then there are 7 packs in total so take away 3 packs and you are left with 4 packs of 4, which is 16 notebooks in total.
