Firstly, I would suggest that we draw a diagram to visualise the problem. Using the diagram and knowledge of rectangles, you can see that the rectangle is made of two right angled triangles. Thus we can use Pythagoras' Theorem, A^2 + B^2 = C^2 to find the length of the diagonal piece of metal. Setting A=5m and B=12m, you can compute that C=13m. Next, you need to find the perimeter of the rectangle. As you know that the length and width are 12 and 5 respectively you can calculate the perimeter to be 5m+5m+12m+12m=34m. Adding the length of the diagonal you can tell that the total length of the metal pieces are 34m+13m=47m. Finally, multiply the total length of the metal pieces by the weight of 1m of metal. Thus 1.5*47=70.5(Answer)