Addition of Ordinates?

[DNAngel]

At the moment, I'm kinda confused about the topic 'Addition of Ordinates'

Apart from adding the y-values of say, f(x) and g(x), can't you just measure the distance one graph is from the x-axis, then add that onto another graph?

Thanks.

[luken93]

Yeah you can measure them if you are looking at the graph, but doing it mathematically will make it look nicer haha

In the end they will look very similar, but if you have to label points wouldnt you prefer it to be exactly to scale?