Let's make a draft to clear the task requirements. It can look the following way:
It is required to calculate the number of tiles that have to be changed, as well as the total time for replacing them. In order to find the number of tiles, we have to calculate the area that needs to be covered and divide it by the area per tile.The ground is square, therefore, we find the total area by multiplying its side by its value
N * N. After that, we calculate the area that the bench takes up by multiplying its two sides as well
M * O. After subtracting the area of the bench by the area of the whole ground, we receive the area that needs to be repaired.
We calculcate the area of a single tile by multiplying its two sides with one another
W * L. As we already stated, now we have to divide the area for covering by the area of a single tile. This way, we find the number of necessary tiles which we multiply by 0.2 (the time needed for changing a tile). Now, we have the wanted output. **