Dev lent Rs. 8000 to Jairam for 17 years and Rs. 4700 to Karnik for 16 years on simple interest at the same rate of interest and received Rs. 21120 in all from both of them as interest. The rate of interest per annum is:
Crop Rotation is the practice of growing a series of dissimilar or different types of crops in the same area in sequenced seasons. It is done so that the soil of farms is not used for only one set of nutrients. It helps in reducing soil erosion and increases soil fertility and crop yield. The British agriculturist Charles Townshend (1674–1738) popularised this revolutionary technique in the 18th century.
If '÷' stands for subtraction,'-' stands for addition,'x' stands for division and '+' stands for multiplication, then which one of the following equation is correct?