i think that the answer is £279.30.
to find the area of the shape you multiply 4.6 by 2.4 which is 11.04.
then you need to work out how many boxes you need by dividing the area by 0.8 which gives you 14 boxes.
you then multiply that by the price per box which was £19.95.
This gave me an answer of £279.30.