find the probability that a leap year selected at random will not have 53 sundays
"there are 366 days in a leap year : 52 weeks and 2 more days . so , 52 sundays and 2 days . these 2 days can be : { mon , tue } , { tue , wed } , { wed , thu } , { thu , fri } , { fri , sat } , { sat , sun } and { sun , mon } ( 7 cases ) . in order to have 53 sundays we should have either { sat , sun } or { sun , mon } case . the probability of that is 2 / 7 . so , probability of not having 53 sundays is 1 - 2 / 7 = 5 / 7 answer : b ."
divide(const_2, add(const_3, const_4))