SIMPLE INTEREST

Rajesh gave 1200 on loan. Some amount he gave at 4% per annum on simple interest and remaining at 5% per annum on simple interest. After two years, he got 110 as interest. Then the amounts given at 4% and 5% per annum on simple interest are, respectively

Same principal is invested in schemes of compound interest and simple interest. The interest obtained in simple interest and compound interest schemes after 2 years are Rs 1200 and Rs 1290 respectively. If the rate of interest is 15%, then what is the principal (in Rs)?

If a sum of money at a certain rate of simple interest per year doubles in 5 years and at a different rate of simple interest per year becomes three times in 12 years, then the difference in the two rates of simple interest per year is