You can solve this using substitution.
y= 9x
y=5x+24
Start by setting the two equations equal to one another.
9x = 5x+24
Put all the x's on one side.
4x=24
x=6
Now, plug the x-coordinate into any of the systems to find the y-coordinate.
y=9x
y=9(6) = 54
x=6, y=54
Hope this helps :)