X does a work in 20 days. Y does the same work in 40 days. In how many days they together will do the same work?	Choose the most appropriate option:	A) 10	B) 12	C) 20	D) 30	E) 13.33

Rationale: x ' s 1 day ' s work = 1 / 20 y ' s 1 day ' s work = 1 / 40 ( x + y ) ' s 1 day ' s work = ( 1 / 20 + 1 / 40 ) = 1 / 13.33 both together will finish the work in 13.33 days . correct option is e
Answer: E