Question

The price of discount airline ticket starts at $150 and increases by $30 each week. Which algebraic expression models this situation?

Answer 1

So we start at `150` dollars. Then we add on `30` dollars per week.

So we have `150` plus `30`, which changes each week. By the second week it's `150 + 60`, week three has `150 + 90`.

So our equation is `150 + 30x`

Answer 2

`150 + 30x`

Explanation:

Since the airline ticket begins at `150`, that is the beginning of the equation:

`150`

But the ticket increases by `$30` every week, so let's start out with that. The first week, the equation is:

`150 + 30`

The second week it would be:

`150 + 30(2) rarr 150 + 60`

The third week it would be:

`150 + 30(3) rarr 150 + 90`

The fourth week it would be:
`150 + 30(4) rarr 150 + 120`

So you can see a pattern. Every week you multiply `30` by the week that it is. We can write this fact algebraically by saying:

`150 + 30(x)`
where `x` is the week.