the tank of molly's motorcycle holds n gallons of gas. Today she bought 4.25 gallons of gas. Write an expression that represents the amount

Well if she filled it with an extra 4.25 gallons then before she filled it it must have has     n - 4.25    gallons in it.

Full tank: n gallons

Amount bought today: 4.25 gallons

Before she filled the motorcyle we know that:

* It must be a non-negative amount of gas in the tank. 

* It was at most n - 4.25 gallons of gas in the tank before she filled it.

(she filled 4.25 gallons into the tank after all)

Therefore the amont of gas g, in gallons can be expressed as follows:

0 ≤ g ≤ n - 4.25         or equaly:         g ∈ [0, n - 4.25]