english: If you have successfully solved the preceding problems you should be able to solve them within a few (say 15) minutes.
non_english: ➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡. ➡➡➡. ➡➡➡➡➡➡➡➡➡➡. ➡➡➡➡➡➡➡➡➡➡. ➡➡➡. ➡➡➡➡➡➡➡➡➡➡. ➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡. ➡➡➡➡➡➡➡➡➡. ➡➡➡➡➡➡➡➡➡➡➡. ➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡➡