4. [20 pts] Recall that a combinatorial proof for an identity proceeds as follows: 1. State a counting question. 2. Answer the question in two ways: (i) one answer must correspond to the left-hand side (LHS) of the identity (ii) the other answer must correspond to the right-hand side (R.HS). 3. Conclude that the LHS is equal to the R.HS. With that in mind, give a combinatorial proof of each the following two identities (a) (2) - 1=2(12-2)+ ("2") where n > 2. (b) (itm - 1) (m+r) Com-1 where m > 1 and r > 0. Solution. Homework 4 CIT 592 (a) your solution to a (b) your solution to b