I would recommend using an app called Desmos graphing calculator for the graph part!
For domain, that’s going to be the distance on your x-axis, which in this case should be something like:
Domain : (-infinity sign, infinity sign)
That’s because the line is continuous, therefore eventually running into all numbers on the x-axis.
Range: (-infinity, 25]
That’s because the highest number the line touches on the y-axis is 25, and continuously goes downwards.
Make sure to put the parenthesis on the infinity signs, and a bracket around 25!