The lengths of the spans are specified by the owner, as is the magnitude of the uniform loads. The lengths of the two inner spans are L = 25 ft and the lengths of the two outer spans are L = 20 ft. The load intensity is qo = 0.4 k/in Young's modulus of the material is E = 29000 ksi. The yield stress is y = 36 ksi, and the maximum deflection is L/200. If each span can have its own cross section, what is the lightest structure you can find? How much difference does it make to have different beams for each span