Try rewriting $y + 12x = 150$ in the form $y = 150 - 12x$. This can make it easier to see what happens when $x$ changes, especially when $x = 0$.

After you plug in $x = 0$, ask yourself: In this story, what moment does $x = 0$ describe? What does the corresponding $y$ value tell you about the activity card?

Type the equation in Desmos as y = 150 - 12x so it is solved for $y$ in terms of $x$.

Click on the gear icon next to the equation and choose "Table" (or use the + button to add a table linked to the equation). In the $x$-column, enter $0$ and observe the corresponding $y$-value in the table; this is the number of credits when no classes are reserved.

Think about what $x = 0$ represents in the story and what the corresponding $y$-value means about the credits on the card. Then choose the answer option that describes that situation in words.

From the problem:

• $x$ is the number of yoga classes reserved.
• $y$ is the number of credits remaining on the activity card.
• The equation that connects them is

The question asks what the number 150 means in this situation.

Solve the equation for $y$ so it looks like "credits remaining" = something involving $x$:

In this form, you can see that $y$ depends on $x$, and 150 is the value you start from before subtracting $12x$.

If no yoga classes have been reserved yet, then $x = 0$.

Substitute $x = 0$ into the equation:

So when $x = 0$ (no classes reserved), $y = 150$ (credits remaining). That means 150 is the number of credits on the card before any yoga classes are reserved, which matches choice B) The activity card initially contains 150 credits before any yoga classes are reserved.