Question

the average daily income of 7 men, 10 woman and one boy is Rs. 12.If the average daily income of the men is Rs 17 and that of the woman is Rs 9, find the boys income per day

Answer 1

let income for boy is x
17+9+x/3=26+x/3
26+x/3=12
x/3=12-26=-14
x=-14*3

Answer 2

average daily income of (7men + 10women + 1boy ) =12 Rs

total number of people take income per day = 7+ 10 + 1 =18

now,
12 ={ 7 ×17 + 10 × 9 + B × 1}/18

12 × 18 = 119 + 90 + B

216 = 209 + B

B = 7

hence, average income of boy = 7 Rs