Hello, Elle,
Ah.
In each way betting the stake is effectively split in two.
Half is on your selection to win.
The other half is on your selection to be placed/in the first three.
If your selection wins you are paid at the winning odds to half the stake, and paid a quarter of the odds for the place stake.
If your selection is placed you are paid at a quarter of the winning odds to the other half of the stake.
In a double bet, the odds for one selection are multiplied by the odds for the other selection.
For example.
A winning £1 double bet on two selections winning at 2-1 and 7-2.
£1 at 2-1 = £2 plus your £1 stake, giving £3.
The £3 goes on the selection at 7-2, giving £10.50 plus the £3, giving a total return of £13.50.
Bookies like multiple selection bets as the odds are against the punter.
The bet they do not like is the single selection bet.
Now, the bit to remember, Elle, is, that betting is a mug's game.
The odds are stacked in the bookie's favour.
You may win in the short term, but over a period of time the bookie wins and you lose.
Is that any help?
I am afraid I am no help in looking for "tailored for the office" jackets other than to ensure there are no holes in them.