A certain sum at a certain simple interest rate % per annum becomes Rs. 7440 in 3 years and Rs. 8400 in 5 years. The principal and rate of interest are
1
Rs. 6400, 7 %
2
Rs. 6000, 8 %
3
Rs. 5700, 9 %
4
Rs. 6700, 4 %
A certain sum at a certain simple interest rate % per annum becomes Rs. 7440 in 3 years and Rs. 8400 in 5 years. The principal and rate of interest are