I am confused about this question please help me. Thank you.

(e) Use a combinatorial argument to explain why the second formula works for selecting a committee of 4 people out of 6. n+1 Consider this formula: ( r + 1 ) : Z (3) for nonnegative integers n and r, r g n. 1.. j:'r (21) Write out the formula for n : 5 and \"r : 3. m+k+1 k: . k ) : 2 (m + j) . Write out the formula for m : 3 and k : 2. (b) A related identity is ( 3 3:0 (c) Use Pascal's Triangle to show the relationship between the answers for parts (a) and (b). ((1) Use a combinatorial argument to explain why the first formula works for selecting a committee of 4 people out of 6