(a)
Computation of amounts
From the sums appropriated therefor, the Secretary of the Treasury shall pay to each State which has a plan approved under this subchapter, for each quarter, beginning with the quarter commencing October 1, 1960—
(2)
in the case of Puerto Rico, the Virgin Islands, and Guam, an amount equal to one-half of the total of the sums expended during such quarter as old-age assistance under the State plan, not counting so much of any expenditure with respect to any month as exceeds $37.50 multiplied by the total number of recipients of old-age assistance for such month; plus
(4)
in the case of any State, an amount equal to 50 percent of the total amounts expended during such quarter as found necessary by the Secretary for the proper and efficient administration of the State plan.