Here's my question:

Fireworks are to be launched from a platform at the base of a hill. Using the top of the platform as the origin and taking some measurements, it was determined that the cross-section of the slope of one side of the hill is y=4x-12 If the path of the fireworks is y=-x^2+15x, calculate the point where the fireworks will land on the hill. (Show your work - 3 marks)

Here's my work on the question:
-x^2+15x=4x-12
x^2-11-12=0
(x-12)(x+1)=0

It needs to be coordinate and can you please show your work for getting the answer,

Thanks you1