The average daily income of 7 men, 11 women and 2 boys is Rs. 257.50. If the average daily income of the men is Rs. 10 more than that of women and the average daily income of the women is Rs. 10 more than that of boys the average daily income of a man is -

Answer: Option C

Let per day income of boy, women, man are = x, x + 10, x + 20
According to the question,
$$\Rightarrow \frac{7M+11W+2B}{20}$$    = 257.50
$$\Rightarrow 7\left(x+20\right)+11\left(x+10\right)+2x$$       = 257.50 × 20
$$\Rightarrow 7x+140+11x+110+2x$$       = 5150
$$\begin{array}{rl}& \Rightarrow 20x=5150-250\\ & \Rightarrow x=\frac{4900}{20}\\ & \Rightarrow x=245\end{array}$$
Per day income of man
= x + 20
= 245 + 20
= 265