69 persons can repair a road in 12 days, working 5 hours a day. In how many days will 30 persons, working 6 hours a day, complete the work?
Pick.
A) 20
B) 23
C) 24
D) 25
E) 26

Rationale: "according to the chain rule , m 1 x t 1 = m 2 x t 2 therefore , 69 x 12 x 5 = 30 x 6 x x x = 23 hence , the number of days = 23 . answer : b"
Answer: B