48+y=x
Explanation: Since we don’t know how many sugar cookies she made They just consider it as y which means some number we don’t know. Since y is how many sugar cookies she made and the question is asking for how many cookies she made in total we have to add 48+y but we don’t know what the answer will be because we don’t know how many sugar cookies she made so therefore you would just put X or another random variable as the answer.