Mary can do a piece of work in 26 days. Rosy is 30% more efficient than Mary. The number of days taken by Rosy to do the same piece of work is?  Choose one:
A) 22 B) 20 C) 24 D) 26 E) 30

Rationale: "ratio of times taken by mary and rosy = 130 : 100 = 13 : 10 suppose rosy takes x days to do the work . 13 : 10 : : 26 : x = > x = 20 days . hence , rosy takes 20 days to complete the work . answer : b"
Answer: B