Compatible residential, commercial, industrial, public and quasipublic uses may be combined, provided that the proposed location of the commercial or industrial uses will not adversely affect or disregard adjacent property, public health, safety, morals and general welfare, and provided further that in a residential- commercial-industrial, residential-commercial, or commercial- industrial development the amount of land devoted to commercial and/or industrial usage shall not exceed fifty percent of the total land area of the development. A variety of housing and building types is encouraged by permitting an increased number of families per acre and by allowing reductions in lot dimensions, yards, building setbacks and area requirements.