Hannah says that her “line graph shows that these figures have held steady” over four months.

A “line (line) graph (graph)” is also a square or rectangular chart, but one that has a line that goes from left to right.

The line goes up or goes down; it changes height to show how something changes.

Usually, a line graph is used to indicate changes over time, over several days or several months or several years.

You could use a line chart to show how gasoline prices are increasing or decreasing over time in the last 10 years.

So if you look at the chart, you see a line, if the line goes up, it's gotten higher, if it goes down, it's gotten lower.

To “hold steady” (steady) means to be constant - to not change.

If prices increase but the amount of money that people earn (people get from their jobs) holds steady, then people aren't going to buy as much.

To “hold steady” means not to change.

If gas prices hold steady, they aren't going up and they aren't going down - they're staying the same.

Since Hannah says that the line graph shows that the figures, or rankings, have held steady over the past four months, this means that the line on the line graph is pretty straight, or flat - it doesn't go up or it doesn't go down very much over this four-month period.