Please help with this Y7 maths homework!

[Celeriacacaca]

Functions

Using two number lines from 0 to 15, draw a mapping diagram to illustrate each of these functions (map each whole number)
a) x ->x+4 (->being an arrow!)
b) x ->3x
etc

Then
The inverse of the function x ->x+1 is x ->x-1. Using three number lines from 0-20, draw a mapping diagram to illustrate each of these functions as well as their inverse functions:
a)x ->4x
b)x->x+5 etc
Clearly I wasn't paying attention at school as I thought it might be y=x+4 in the first example rather than x arrow x+4 which I just don't understand. Help please?

No idea but if nobody's come to your rescue by 9.00 when I pick my year 8 up I'll ask him!

Draw two number lines next to each other, from 0-15, with the numbers lined up with each other.

For x->x+4, then draw a line with an arrow from 0 on one number line to 4 on the other, 1 maps to 5 and so on.

What noblegiraffe said. Number lines are virtical.

The arrow thing is just a different way of saying y = x + 4 really.

Brilliant, thank you. I am so grateful to you all.

I agree with noblegiraffe

That said I think I would find this even more complicated than the complicated way my DD was introduced to algebra using function boxes.