I have another question, hopefully not as daft as the one I asked mamahanji
Currently there are a lot of tempting bookie offers especially as both Royal Ascot and World Cup of bet for x plus y to win and get enhanced odds of z. Across sports as well, so horses/horses, horses/football etc.
I know that to benefit from these
a) lay odds multiplied are less than the back,odds
b) the events can’t be simultaneous and you have to lay in sequence
c) if the first one loses its game over
My question is what odds to use in the calculator when calculating the lay amount.
So in a very crude hypothetical example:-
Bookie is offering ASpanishNamedHorse to win the 3.20 at Ascot plus Spain to beat Japan in the World Cup that evening at odds of 9.
3.20 Royal Ascot - ASpanishNamedHorse (normal back odds 2, lay 2.5)
6.00 World Cup Match - Spain to beat Japan (normal back odds 2.5, lay3)
My question, I’m rubbish at maths but can follow directions when I know what they are! On the calculator I use to work out my first lay bet, do I enter
I back £10, therefore I lay £10 (?), at the odds of:-
Back: 9
Lay: 2.5
Or
Back: 2
Lay: 2.5
Or something entirely different 
Thanks to anyone taking the time to answer. I feel I’m getting more from this thread than I’m putting in, but maybe this particular question can help any newbies as well.