Four friends buy cinema tickets using this offer. Cinema tickets
Buy 3 tickets and get a tickets free
They each pay £6.15
How much does a ticket cost

Step-by-step explanation:

The cost of one ticket will be  £8.20

Explanation

Suppose, the cost of one ticket is  

As the offer says "buy 3 tickets and get a ticket free" , it means they actually need to pay for 3 tickets.

So, the total cost of 3 tickets  

Each of four friends pay £6.15 , so the total amount they pay  

=£6.15*4=£24.60

Thus, the equation will be

=3x=24.60

=x=24.60/3=8.20

 So, the cost of one ticket will be  £8.20

entering that problem on the tube might get you an answer