How was plumbing done for 1950's houses constructed on a concret slab?

The concrete slab that my 1954 desert ranch house sits upon shows several cracks and uneven areas. Apparently there is one drain for the kitchen and laundry, and one drain for the bathrooms in this 1300 sq. ft. house. Since the kitchen drain stopped working and the heavy duty router failed, I know the next step is professional. Yet I would like to know how the drains were first constructed. I just can not visualize. Would anyone know of any sites or references I could use to find out?

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