Ответ:а) 80!/79! + 59!/58! = 80+59 = 139.б) 10!·13!/(8!·15!) = (10·9)/(15·14) = 3/7.в) (5!+6!)/4! + (7!·4!)/10! = (120+720)/24 + (7·6·5·4!)/(10·9·8·7·6·5·4!) = 35+1/30 = 1051/30.г) 14!·15!·20!/(13!·16!·21!) = 14/(16·21) = 1/24.