The wall has an area of 10mē. To calculate the amount of rolls you must divide this area by :

But you can't buy a roll therefore you need 4 single rolls.

If 1 kg of nails cost 16 cts. than 2 kg = 1 kg + 1 kg will cost 16 cts. + 16 cts. = 32 cts.

(By the way: Are you certain that you didn't know how to do this problem?)

1. Calculate the area of one tile:

2. Calculate the total area

3. Divide A by a to get the number of tiles. Be aware that you can't buy any fractions of tiles.