google sheetsgoogle-sheets-charts
For some reason Google Spreadsheet insists on using the data I wish to have for my x-axis as my y-axis. Here I'll show what happens when I try to use my data to form a chart, and what happens when I use Google's example data for creating a line chart.
Here is the image (my data is on the right, example data on the left):
What you need to do is a few steps:
tldr; the Google Support answer is broken for a few chart types. Do your Axis assignments with Line charts, and change the Chart Type after.
My understanding of your requirement is as below, though this does not apply your sample data:
The layout of the left four columns is required - in effect I have substituted:
10 100
30 110
60 150
80 180
for your sample data in the OP.
I selected the data area, Charts, Charts, Line and checked both Use row 1 as headers and Use column A as labels. This ended up with the appearance of a scatter plot but in Advanced edit..., Customise, Features this, oddly, was fixed by checking Plot null values.
The colours, datapoints etc were customised for the image.
Best Answer
Never mind, I found the solution.
It was because my data was text format (despite changing the formatting many times in the format options). To counteract this I had to make another table which used =VALUE(cell) on each piece of data. This gave me the numerical value allowing me to make graphs successfully.