- Tiles are sold in boxes with 21 tiles in each box.
The tiles are laid out in \(x\) rows of 5 tiles and \(y\) rows of 6 tiles.
All the tiles from a box are used before the next box is opened.
When all the rows of tiles have been laid, there are \(n\) tiles left in the last opened box.
- Write down a congruence expression for \(n\) in the form
$$a x + b y ( \bmod c )$$
where \(a\), \(b\) and \(c\) are integers.
Given that
- exactly 43 rows of tiles are laid
- there are no tiles left in the last opened box
- use your congruence expression to determine the minimum number of rows of 6 tiles laid.