Subject: mathqa
Question: the average earning of a person for the first 4 days of a week is rs 18 and for the last 4 days is rs 22 . if he earns rs 20 on the fourth day , his average earning for the whole week is ?
Option: 
A: rs 18.95
B: rs 25.71
C: rs 20
D: none of these
Answer: C