you need 18.24 square inches of foil to cover the chocolate
the area of the square on the bottom is 1.44 in^2
to find the area of 1 triangle do 1.2 times 3.5 = 4.2
to find the area of the 4 triangles multiply 4.2 by 4 to get 16.8 in^2
to find the total area of the figure (and the amt of tinfoil needed) add 16.8+1.44 to get 18.24 in^2
