Question

solve 7 th c part
plsss​

Answer 1

Step-by-step explanation:

your answer is here and hope

Answer 2

P(n,r)=2520

(n−r)!n!=2520...(1)

C(n,r)=21

r!(n−r)!n!=21....(2)

comparing (1) and (2), we get,

r!2520=21

∴r!=120