A field in the form of a parallelogram has one side 150 metres and its distance from the opposite side is 80 metres. The cost of watering the field at the rate of 50 paise per square metre is :

$$\eqalign{ & {\text{Area of the field}} = \left( {{\text{Base}} \times {\text{Height}}} \right) \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = \left( {150 \times 80} \right){m^2} \cr & \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, = 12000\,{m^2} \cr} $$
∴ Cost of watching :
$$\eqalign{ & = {\text{Rs}}{\text{. }}\left( {12000 \times 0.50} \right) \cr & = {\text{Rs}}{\text{. 6000}} \cr} $$