The breadth of a rectangular field is 60% of its length. If the perimeter of the field is 800 m, find out the area of the field.

A tank is 25 m long, 12 m wide and 6 m deep. What is the cost of plastering of its walls and bottom at the rate of 75 paise per sq. m?

On my sister's 15th birthday, she was 159 cm in height, having grown 6% since the year before. How tall was she the previous year?