x and y co-ordinates
A good way to remember which axis is which is to say to yourself;
'x is a cross so the x axis is across'
Co-ordinates are written as two numbers, separated by a comma, within round brackets.
For example, (2, 3), (5, 7) and (4, 4)
Remember: Co-ordinates are written alphabetically - so x comes before y (x, y)