A certain sum becomes Rs.1,050 in 5 years and Rs.1,230 in 8 years at simple interest. What is the sum?

Rs. 750

Principal (P) becomes 1050 in 5 years and 1230 in 8 years

i.e. Interest (I) of 3 years = 1230-1050 = Rs 180

Interest of 1 year = \(\frac{180}{3}\) Rs 60

Interest of 5 years =60×5=Rs 300

Principal=Amount-Interest

P=1050-300

Principal = Rs 750