Students at this stage might or might not be able to read set notation yet as they usually do not usually learn terms in set notation and theory at this stage (most students learn this either in late Sec 3 or early Sec 4).

Similarly, the words “and” and “or”, which are seemingly harmless, are somehow misused by students to a certain degree.

Indeed, students in most secondary schools do not learn to express ranges in set notations. Expressing ranges in set notations is usually taught at tertiary level.

It is true that the difference between "and" and "or" is not apparent to all. Just in case you are confused, "or" is for disjointed ranges, but are all solutions nevertheless. In the first question, x<0 and x>2 are disjointed, but both are solutions. In this event, "or" is used to indicate that.

As for "and", it is used when there are two or more ranges that are conditionally possible, but that all the conditions must be met in order for the solution to be valid. In the second question, x>3 "and" x>0 present the situation where both conditions must be met. Since x>3 is able to fulfil all required conditions, it is the final solution.

I hope this clarifies.

Thank you for the clear solution.