We have been given Asim is going to cover the path with paving. Each paving stone is a square of side 30 cm.
Let us find area covered by each stone.
Since the paving stone is square, so it area would be square of each side length.

The dimension of rectangular path are 630 cm and 120 cm.
We know that area of rectangle is width times length, so area of garden would be length times width.

To find the number of stones, we will divide area of path by area of each stone.


Therefore, it will take 84 stones to cover the path.
We have been given that each paving stone costs £2.50, so total cost would be
.
Therefore, it will cost £210.