Question 9
Alice and Billy live in the same apartment building. Units 0 to 9 are on the 1st floor, units 10 to 19 are on the 2nd floor, units 20 to 29 are on the 3rd floor, and so on. Alice’s unit number is on the floor that matches Billy’s unit number. If the sum of their unit numbers is 255, what is the unit number of Alice’s apartment?