n is just a placer holder for how many days the Carter family can vacate.
That being said, the question says that they will spend 275 per day, which is per n. You want to multiply 275 by n.
Then the question says it plans to spend $1000 on meals (that's a lot). Instead of substracting, you are going to add for this equation. You want the equation to match; you want both sides to equal 2700 so you can determine how many days you can spend there.
According to the Exterior Angle Theorem, the exterior angle is equal to the sum of the interior angles opposite from the exterior angle. In other words:
