A group of pupils stood in three rows. The 1st row had 6f pupils. The 2nd row had 3f fewer pupils than the 1st row. The 3rd row had 4 more pupils than the 2nd row.
- Find the number of pupils in the 3rd row in terms of f. Give your answer in the simplest form.
- There were 31 pupils in the 3rd row. Find the value of f.