CCommunity
We know that, formula for simple interest:
$(S.I. = \frac{{P \times R \times T}}{{100}})$
Where,
S.I. = Simple Interest
P= principal
T = Time
R = Rate of interest
Interest payable to A = 3500 × (10/100) × 3 = 1050
Interest payable to B = 3500 × (11.5/100) × 3 = 1207.5
The basic amount in both transactions is same. So, difference between interests in two transactions is the gain.
∴ B’s gain = amount B gets – amount B has to pay = 1207.5 – 1050 = 157.5