A certain number of persons can complete a work in 54 days. If there were 15 persons less, it would take 18 days more for the work to be completed. Initially, the number persons is:
A certain sum amounts to Rs 8,192 in 3.5 years and to Rs 9,472 in 6 years, at simple interest at a certain rate percent p. a. The rate of interest p.a. and the sum are ........ and ....... respectively.