Aₐᵇ = a!/(a-b)!
a! = 1*2*3*....*(a-1)*a
A₆² = 6! / (6-2)! = 6!/4! = 4! * 5*6/4! = 5*6 = 30
5,48+4,52=10
(5/15)*(6/15)+(10/15)*(9/15)=120/(15*15))=8/15
3х-7<4х+8