See Figure. For the 30-ft span, L, = 10 ft. For the 36-ft span, L, = 9 ft. Use Fy = 36 ksi. Select the lightest W section that is satisfactory for the 30-ft span. Use this W section in the other span...

See Figure. For the 30-ft span, L, = 10 ft. For the 36-ft span, L, = 9 ft. Use Fy = 36 ksi. Select the lightest W section that is satisfactory for the 30-ft span. Use this W section in the other span and design a pair of cover plates only in the region indicated by a heavy line.