Question

When josh babysits,he charges a flat fee of $4 plus an hourly rate or r dollars

Answer 1

The question doesnt seem to be repeated. From here, I'm just going to assume the hours he worked is 4. Heres what the equation would look like.

4x + 4 = r

r = total money earned
x = cost per hours worked
The plus 4 is the flat fee he charges,

Answer 2

I think what you are looking for is the equation on how this could be displayed.
The baseline is 4, and the hourly rate of r.
This can be shown by:
4 + r = cost