You can 
put this solution on YOUR website!  
Hi
He spends £10 on a meal and then one-quarter of what he has left on a taxi home. 
He now has half of what the  he started with.
he started with.
Best to Set it Up Algebraically:
   |Multiplying thru by 4 so as all denominators = 1
  |Multiplying thru by 4 so as all denominators = 1
    4x-40 - (x-10) = 2x
            x = £30, amount he started with
and...
£30 - £10  - £5 = £15