I need help on this question please and thank you that would be great

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

X+ y = 5 ; x - y =3 solve using linear combination

Kayaks rent for $35 per day. which expression can you use to find the cost in dollars of renting 3 kayaks for a day?