Concept:Use the simple interest formula SI=100P×R×T​ to solve for principal P.Explanation:Given: SI=28600, R=2.5% per annum, T=3 years 3 months =3.25 years.Rearrange formula: P=R×TSI×100​.Substitute values: P=2.5×3.2528600×100​.Calculate denominator: 2.5×3.25=8.125.Numerator: 28600×100=2,860,000.Divide: P=8.1252,860,000​=352,000.Answer:The sum of money is ₹3,52,000.