Check the picture below.
well, we know the weight of the steel used for the gate is 2.5 kg per metre, how long is the gate in total?
well, we know the vertical sides are 5 metre each, the horizontal ones are 12 metre each, and the diagonal ones are 13 metre each, that means the gate is 5+5+12+12+13+13 = 60 metres.
since each metre weights 2.5 kgs, so 60 metres will be then 60 * 2.5 = 150 kgs total.
