what is the probability of getting 53 mondays in a leap year ?
"in a leap year contains 52 monday ' s since 52 weeks are present and 2 days extra it may be sunday and monday 2 . monday and tuesday 3 . tuesday and thursday 4 . thursday and friday similary 7 alternatives are possible . among this only 2 are possible cases so 2 / 7 answer : b"
divide(const_2, choose(add(const_3, const_3), const_3))