Enough means adequate or to the required degree. It has a positive meaning.
Too means ‘more than is necessary or wanted’. It has a negative meaning.
Answers
1. The coat was too expensive, so I didn’t buy it.
2. If the water is warm enough, we can go for a swim.
3. His theories are too difficult to understand.
4. We didn’t manage to sell enough tickets.
5. There were too many people at the party.
6. She is experienced enough to handle this job.
7. She is too immature to handle the situation.
8. It is never too late to start.
9. Both ‘too old’ and ‘old enough’ are possible here with different meanings. She is too old to have a baby. (= She cannot have a baby now because she is too old.) / She is old enough to have a baby. (= She is of the right age to have a baby.)
10. I quit because I had had enough of their quarreling.
