So, you've got two value for volume, which will be on the y-xis, and two value for temperature, which will be on the x-axis.
After you draw these two points on the graph, extend the line until it intersects the x-axis - this is the point where volume is zero. Notice that you'll get a negative value for temperature - good, it means you've drawn it correctly.
Here's a very rough sketch of what the graph will look like
As you can see, this is very loosely drawn.
You must determine the value of the temperature where volume is zero.
To do this, use the two points you have to calculate the slope of the line by
Now use the slope and one of the two given points to find the value of the
Determine the percent error by
SIDE NOTE Ignore the minus signs of the temperatures when doing the percent error calculation.