The cost of a disc holder is 25p.
john has £15 to spend

what is the greatest number of compact disc holders can john buy for £15?

Let us first look at all the important information’s that are provided in the question. Based on these details the answer to the question can be easily found.
Amount that John can spend = 15 pounds
Cost of each disc holder = 25 p
                                        = 0.25 pounds
Then
Maximum number of discs that John can buy = 15/0.25
                                                                         = 60
So John can buy 60 discs.Hope this is what you were looking for.

If you would like to know what is the greatest number of compact disc holders John can buy for £15, you can calculate this using the following steps:

£15 / 25p = £15 / £0.25 = 15 / 0.25 = 60 compact disc holders

Result: The greatest number of compact disc holders would be 60.