A man invests some amount of money for some time period. This amount becomes Rs 4500 at the rate of 7 percent simple interest. However, if invested at 5 percent per annum simple interest, the same amount becomes Rs 3500. Find the amount of money and the time period.

The sum invested is Rs 1000 for 50 years.

At 7% SI the amount is P(1 + 7t/100) = 4500.

At 5% SI the amount is P(1 + 5t/100) = 3500.

Subtracting, P x 2t/100 = 1000, so P x t = 50000.

Using 3500 = P + 5(50000)/100 = P + 2500 gives P = 1000, then t = 50000/1000 = 50.

Method: simple interest amount equations solved simultaneously.