(1) An amount which, with all moneys received from the Commonwealth applicable thereto, shall be sufficient to pay the minimum salaries and increments of the teaching and supervisory staff thereof as fixed and provided by law and to pay the contributions of said district to the teachers' retirement system. For the purpose of computing the amount required to pay the minimum salaries and increments fixed by law, but without otherwise limiting the rights of the district to employ teachers or other employes, (i) The number of teachers on the salary schedule of the elementary schools shall not exceed one for every thirty pupils in average daily membership in such schools, (ii) The number of teachers on the salary schedule of the junior high schools shall not exceed one for every twenty-two pupils in average daily membership in such schools, (iii) The number of teachers on the salary schedule of the senior high schools shall not exceed one for every twenty-two pupils in average daily membership in such schools, (iv) The number of teachers with salaries and increments fixed by law, on any salary schedule now established or hereafter established, and not specially mentioned in this act, shall not exceed one for every twenty-two pupils in average daily membership, (v) The number of principals in the elementary schools, and the principals in charge of all other character of schools now established or hereafter established, and not specially mentioned in this act, shall not exceed one for every six hundred pupils in average daily membership in such schools, (vi) The number of principals in the junior and senior high schools shall not exceed one for every twelve hundred pupils in average daily membership in such schools, (vii) The number of supervisors in all schools shall not exceed one for every fifteen hundred pupils in average daily membership, (viii) The number of attendance officers and home and school visitors shall not exceed one for every two thousand pupils in average daily membership in all elementary and secondary schools, (ix) In all adult and extension school classes, the number of teachers shall not exceed one for every twenty pupils in average daily membership in such schools.

The salary and increments, fixed by law, of members of the teaching and supervisory staff whose number is not in some manner limited hereby, shall not be included within the purposes authorized by clause (1) of this section, but shall be construed and regarded as constituting expenses within the meaning of clause (3) of this section.

Average daily membership, as used herein, shall be based upon membership during the preceding school term.

(2) An amount sufficient to pay the interest on, and retire at maturity the principal of, the indebtedness of said district incurred as authorized by law.

(2.1) An amount sufficient to pay any rentals agreed to be paid to the State Public School Building Authority or any other authority created by the General Assembly, having State-wide jurisdiction.

(3) An amount sufficient to pay all other expenses and requirements of said school district, which amount shall be equivalent to not less than three, nor more than five, mills on the dollar of the total assessment of all property assessed and certified for taxation therein.

The total annual school tax levy for all purposes in any school district of the first class shall not be more than eleven and three-quarter (11 ¾ ) mills on the dollar of the total assessment of all property assessed and certified for taxation in the territory constituting the district.