Help me with arithmetic sequences.

X=1 2 3 4 5
Y=18. . . . -10

Ineed to know the answer right now! !

You're locked out of your house. the only open window is on the second floor, 25 feet above the ground. there are bushes along the edge of the house, so you will need to place the ladder 10 feet from the house. what length ladder do you need to reach the window?

If a company produces x units of an item at a cost of $35 apiece the function c=35x is a of the total production costs