by using the rules of inference how can I prove that:

(AvB)n(AvC) concludes Av(BnC)

I know how to prove it the other way round using rules of inference but when i try to prove it this way I get stuck. Here is my work:

1 (AvB)n(AvC) hypothesis

2 (AvB) n-elimination on line 1

3 A Assumption

4 Av(BnC) v-introduction on line 3

5 B Assumption

I don't know how to continue this proof using rules of inference. Any help appreciated.

thanks.