The process you refer to is known as Functional Decomposition. A link which might help you understand the process:
I don't really understand how to draw a graph by adding 2 together. Please could you help me. The graph I have to draw is
y = abs ( 1 - x) + x
I know what the modulus of (1 - x) looks like, and I know what y =x looks like, but I don't know how to "add" them on one axis to make it one graph.
Please could someone explain this.