Can we use both
|| in one expression?
You can. For example:
age < 18 && parentSupervision || age >= 18. It is advisable to use () to group each of those statements because it can get a little confusing at times. This expression says: if age is less than 18 but parentSupervision is true, the expression is true. Otherwise if age is greater than or equal to 18, the expression is also true.
&& takes precedence over
|| when it comes to order, which is why it reads this way instead of: (age is less than 18) and (either parentSupervision is true or age is greater than or equal to 18).