We've already learnt about number planes, which are also called Cartesian planes or coordinate planes.
Just to recap, a number plane is created by two perpendicular lines that we call an $x$x-axis and a $y$y-axis.
The $x$x-axis is the horizontal line and the $y$y-axis is the vertical line.
Where the two axes cross each other is labelled the origin. It has a zero value on both axes.
Both axes have positive and negative values which are divided by the origin as shown in the diagram below.
We can create a grid from the $2$2 number lines. When labeling points on the grid, we always use the $x$x-value first.
A ratio compares the relationship between two values. It compares how much there is of one thing compared to another. We can also plot pairs of ratios on a number plane. It's a very similar process.
For example, if I wanted to plot the ratio $3:19$3:19 on a number plane, I would plot the coordinate $\left(3,19\right)$(3,19). The green dot in the diagram below shows that coordinate. In other words, the $x$x value is $3$3 and the $y$y value is $19$19.
Plot $13:9$13:9 on the coordinate plane.
Plot $13:17$13:17 on the coordinate plane.
Consider the given graph.
a) What ratio has been plotted?
b) Which option could be being represented by this graph and ratio?
A) For every 2 green sweets in a mix, there is 1 red sweet.
B) For every 1 green sweet in a mix, there are 2 red sweets.