The table below shows the number of books read by five children in one month.
| Name | Number of books |
|---|
| Joshua | ? |
| Zachary | 7 |
| Gabrielle | 16 |
| Aidan | 9 |
| Isaac | 18 |
If Joshua read 5 books less than
of the total number of books read by the other four children, then how many books did Joshua read in a month?