Graph and equation both shows the proportional comparison between two quantities
for example, equation y = 4x, this means, the value of 'y' will always be 4 times the value of 'x'
More complex equation such as y = 3x + 5, means that the value of 'y' equals to 5 more triples of value of 'x'
Another example is the conversion graph attached below, it shows the relationship between kilometers and miles. For example, we want to find out how many miles are in 10 kilometers, we would draw a line from the point that shows 10 km towards the graph, then across from the graph to miles, and we'd get a reading of 12 miles.