22. If Rs. 64 amount to Rs. 83.20 in 2 year, what will Rs. 86 amount to in 4 years at the same rate per cent per annum?

23. A sum of Rs. 2540 is lent out into two parts, one at 12% and another one at 12 %. If the total annual income is Rs. 311.60, he money lent at 12% is:

24. Rs. 800 amounts to Rs. 920 in 3 years at simple interest. If the interest rate is increased by 3%. It would amount to how much?