The average daily income of 7 men, 11 womenand 2 boysis 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 womenis Rs.10 more than that of boys, the average daily income of a man is

given the average income of 7men,11 women and 2 boys is 257.5

let the amount of men be M

women be W and boys be B

so 7M+11W+2B/7+11+2=257.5

so 7M+11W+2B=20*257.5

7M+11W+2B=5150

given that avg daily income of men =10+W----1

W=10+B-----2

M+20+B------3

we need to find the average income of men

so convert equation 1,2,3 in form subjective to M

so

now the average is 7M+11(M-10)+2(M-20)/20

7M+11M+-110+2M-40=5150

20M-150=5150

20M=5300

M=265

hence answer is optionC