I can't see the whole pic...
what is written on the side?? I can see part of it and I think it is telling you what to do. If not what is thew question?? All you are showing is the lines.
Website A:
c = 10 + 0.25 s
where c is the cost and s is the number of songs.
Website B:
c = 0.75 s
The equation ( answer ):
10 + 0.25 s = 0.75 s
We can solve this equation:
10 = 0.5 s
s = 10 : 0.5
s = 20 ( Marvin would have to buy 20 songs to to make the costs equal )
125 > 50 + 4.25*p
subtract 50 from each side
75 =>4.25p
divide by 4.25
p>17.64
He may invite up to 17 people ( if he doesn't have to pay for himself)
He may invite 16 if he has to pay for himself
If you are meaning Nine times Nine the answer is 81.