Question

if 6pr=60 then 6cr = 15

Answer 1

6pr= 60
6!/(6-r)! = 60 ----1

6cr = 15
6!/[r! *(6-r)!] = 15----2

1/2

6! gets cancelled and (6-r) ! Gets cancelled
(1/1)/(1/r!) becomes r!
r! = 24
r! = 4!
Therefore r = 4