The product of the slopes would be -1 because the slopes of two lines that are perpendicular are opposite reciprocals (ex. 2 and -1/2 multiplied together would be -1)
My mom just helped me with it, so I don't know if it's exactly alright. She said it was 20, but theres no 20 as I checked, and I don't know if she didn't right. I got a whole 25.