What does ø mean ? Can someone explain it based off the problem in the photo ?

It means something mathematical

Step-by-step explanation:

The slashed zero glyph is often used to distinguish the digit "zero" ("0") from the Latin script letter "O" anywhere that the distinction needs emphasis, particularly in encoding systems, scientific and engineering applications, computer programming (such as software development), and telecommunications.

true? is that what you're asking or do you mean something else?