Answer:
C=x+200
the y intercept is 200.
the y intercept represents $200 after 0 phones
This is a mutually exclusive event because you can't choose both at the same turn you can only pick one or the other. so we add the event chances together,
5/35 + 10/35 = 15/35 or reduced 3/7
X = -1/15y+7/3
I hope this helps! :>