On x axis we will need 24 feets of material. on y axis we will need 2 times 2 feet which is 4 feet for those sides.
now there are lines that are not paralel to x and y so it is not that simple (but not hard either) to calculate lenghts. we can use formula for distance between 2 dots.
we will use dots: (12,7) and (0,2)
from that using pythagoras theorem we can see that distance is:
d = √12^2 + 5^2 = 13
Total lenght is:
2*13 + 24 + 4 = 26 + 28 = 54