Translate into an algebraic expressions: A number increased by a % and decreased by 80% is 400. What is the number ?

What is the range? can’t seem to find it out

David leaves his house to go to school. he walks 200 meters west and 300 meters north. how far is david from his original starting point?

My final challenge question of the day! i have no tests, nothing to do this for, it is simply giving away free points for a you tube video! so 50 free points for answering the most simple question ever! here is the key to getting brainiest for this question. answer in under 50 seconds. you think you can do it. i think you can. here is the question: 1x2= i know! easiest question ever! and yes! if you answer this question, you will be on you so come on and get the free 50 while you can!