What's the next number?
7594, 3649, 9253,

7594 - 3649 = 3945

So, from the first number to the second number we are subtracting 3945.

9253 - 3649 = 5604

So, from the second number to the third number we are adding 5604.

Now, from the third to the fourth number we should subtract 3945. And them from the fourth to the five number we should add 5604. And so on.

7594, 3649, 9253, 5308, 10912, 6967, 12571, ...

7594 - 3649 = 3945
I subtracted 3945
9253 - 3649 = 5604
I subtracted 5604
Together I added 5604 from the second to the third number
So now the pattern is to subtract
 3945
and then add
5604
7594⇒3649⇒9253⇒5308
I did that by doing: 9253-3945
Hope this helps

Yes you do, so £1973.09 - £1473.50 = £499.59 so tim overpaid £499.59 .hope this ; )