Prove for all integers n, k, and r with n ≥k≥r that (O)(=O(-) Lify both sides.) n n- r

hello, I appreciate your answer but the answer looks funny it is difficult to understand. Would you please rewrite the answer in a way I can understand? Thank you.

I am not quite sure what you did in this question even though the answer is right. Is it possible to use a pen instead of typing ? That can be a great help. Thanks.

im still confused