If ₹64 amounts to ₹83.20 in 2 years on simple interest, then how much will ₹86 amount to in 4 years at the same rate percent per annum?

₹137.60

Principal P1 = 64

Time T1 = 2 years

Amount A1 = 83.20

Simple interest S1 = A1 - P1 = 83.2-64 = 19.2

Assume Rate per annum, R1

19.2 = 64*2*R1/100

R1 = 1920/128

If P2 = 86

T2 = 4 years

and R2 = R1

Then, S2= 86*4*1920/(128*100) = 86*60/100 = 51.6

A2 = P2+S2 = 51.6+86 = 137.60

The correct answer is Option (4) → ₹137.60