The answer is A. As the friend spends $30 getting into and buying food at the fair. So he has $70 left. That means c and d are not right.
To find the number of rides he/she can go on we would need to subtract the number of rides times -2 as he/she is losing money.
So 70 is positive and you are subtracting 2 times the amount of rides (-2).
So the answer is A.
I hope this helps!