If Rs. 64 amount to Rs. 83.20 in 2 years. What will Rs. 86 amount to in 4 years at the same rate percent per annum?

S.I on Rs. 64 for 2 year = Rs. 19.20
∴ Rate = (100 x SI) / (P x T) = (100 x 19.20) / (64 x 2) = 15%
∴ S.I On Rs. 86 for 4 year = (P x R x T) / 100 = Rs. (86 x 4 x 15 ) /100 = Rs.51.60
∴ Amount of Rs. 86 after 4 years = Rs. (86 + 51.60) = Rs. 137.60