The x-axis is labeled in thousands of steps, not single steps. Keep track of that unit while you work.

After you have an equation for the line, substitute $250$ for $y$ and solve for $x$, then convert from thousands of steps to steps.

Enter the points

• A=(5,140)
• B=(11,260)

Compute the slope with an expression like

• m=(260-140)/(11-5)

Then enter the line

• y=m(x-5)+140

Enter y=250 as another line. Click the intersection point of the two lines and note the x-coordinate (this x-value is in thousands of steps).

Multiply the x-coordinate you found by $1000$ to convert from thousands of steps to steps, then select the matching option.

From the graph, the line of best fit passes through the labeled points $(5,140)$ and $(11,260)$, where $x$ is measured in thousands of steps.

The slope is

So the model increases by about $20$ calories per additional 1 thousand steps.

Use $y=20x+b$ and the point $(5,140)$:

So an equation for the line of best fit is $y=20x+40$, where $x$ is in thousands of steps.

Set $y=250$:

This means about $10.5$ thousand steps.

Since $x=10.5$ represents $10.5$ thousand steps,

So the predicted number of steps is $10{,}500$. Therefore, the correct choice is $10,500$.