This is pretty simple, you just add up the percentages and that would give you 65%, now you figure out 65% of 320 and google will tell you it is 208. now you have two possible answers, i am not sure if your question is asking for a percentage or an exact amount if it is parentage the it would be 35%, if it is exact then it would be 320-208 which is 112. so your answer probably is 112 students chose other.
