A building contractor employs 20 male, 15 female and 5 child workers. To a male worker he pays Rs.25 per day, to a female worker Rs.20 per day and a child worker Rs.8 per day. The average wage per day paid by the contractor is__________?
A. Rs.20
B. Rs.21
C. Rs.22
D. Rs.23
20 15 5
25 20 8
500 + 300 + 40 = 840/40 = 21