please explain how I find the y and x intercepts without using a graph.

My plot points are (-30,0), (-15,15), (0,30), (15,45), (30,60)

Please explain. I do not want just the answer. Normally, I can draw a graph to get the answer, but this graph would go all the way to 60 so I would be drawing forever. I tried searching for an online graph creator, but none of them helped.

Is there a way to find the intercepts without looking at a graph? I am not that good at math so please explain in detail.

Thank you in advance!!