How long will it take a certain amount to increase by `30%` at the rate of `15%` simple interest ?

In how many years will a certain sum amounts to 6 times itself at 25% per annum simple interest ?

A certain sum becomes X 600 in a certain time at the rate of 6% simple interest. The same sum amounts to X 200 at the rate of 1% simple interest in the same duration. Find the sum and time.

How much time will it take for an amount of ₹360 to yield ₹72 as interest at 5% p.a. of simple interest?

A borrowed a certain sum of money from B at the rate of 10% per annum under simple interest and lens one-fourth of the amount to C at 8% per annum under simple interest and the remaining amount to D at 15% per annum under simple interest. If the end of 15 years. A made profit of Rs 5850 in the deal, then find the sum that A had lent to D.

A borrows Rs. 800 at the rate of 12% per annum simple interest and B borrows Rs. 910 at the rate of 10% per annum, simple interest. In how many years will their amounts of debt be equal ?