A sum of ₹1,600 amounts to ₹1,840 in 2 years at simple interest. At what rate of interest per annum?

SI = 1840 - 1600 = ₹240। दर R = (SI x 100) / (P x T) = (240 x 100) / (1600 x 2) = 24000 / 3200 = 7.5%।