For problems like this in the future, pay attention to the order of words, and how they go together! For example- "the difference of 23 and a number" means to subtract a number from 23, whereas "the difference of a number and 23" would mean to subtract 23 from the number. Words like "increase" and "sum" both mean addition; "product" and "times" both mean multiplication; "difference" and "less" mean subtraction. Just keep these in mind (and watch for context)!
