24. If a is the base amount expenditure, b is the increase in the operation cost? each year over a period of n years, the total cost of maintenance is :
25. Renu Bala deposits Rs 1200 now Rs 800 two year from now and Rs 1000 five years from now. If the savings bank's rate of interest in 5%, she will receive an amount of Rs X 10 years from now, where X is
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