I’m canadian so I’m not quite sure how the money itself works, but I can explain how to do them. The easiest way is to divide each option by the number of items per price. For example, in A option 1 is already 1 ticket/ £8 whereas in the second it’s 3 tickets/ £20. So divide both the 3 and the £20 so you get the price per individual ticket. In the end you get 1 ticket/ £6.66 meaning it is a better deal than option 1.