A man and a boy received Rs. 800 as wages for 5 days for the work they did together. The man's efficiency in the work was three times that of the boy. What are the daily wages of the boy ?

Ratio of 1 day's work of man and boy = 3 : 1
$$\eqalign{ & {\text{Total wages of the boy}} \cr & = {\text{Rs}}{\text{.}}\left( {800 \times \frac{1}{4}} \right) \cr & = {\text{Rs}}{\text{. 200}} \cr & \therefore {\text{Daily wages of the boy}} \cr & = {\text{Rs}}{\text{.}}\left( {\frac{{200}}{5}} \right) \cr & = {\text{Rs}}{\text{. 40}} \cr} $$