25 tickets must be purchased for the total cost at carnival M and carnival P to be the same.
<u>Step-by-step explanation:</u>
It is given that,
Carnival M charges an entrance fee of $5.00 and $0.65 per ticket for the rides.
Let us take, the total cost as 'y' and the no.of tickets as 'x'
The total cost at carnival M = Entrance fee + (cost per ticket × no.of tickets).
⇒
-----------(1)
Carnival P charges an entrance fee of $10.00 and $0.45 per ticket to ride.
The total cost at carnival P = Entrance fee + (cost per ticket × no.of tickets).
⇒
--------(2)
<u>The total cost at carnival M and carnival P to be the same :</u>
Comparing equations (1) and (2),
⇒ 
⇒ 
⇒ 
⇒ 
Therefore, 25 tickets must be purchased in order for the total cost at carnival M and carnival P to be the same.