What is the percent of change From 200 to 500

Me! 50 points! why does when we come home, our door is unlocked and there is grease on the door knob, me solve this , and i don't know what category this goes under

If a baby uses 15 diapers in 2 days how many diapers will the baby use in a year

Hi i’m not sure how to do question 20 if u could explain how to do it that’d b great