this is with the 40% off welcome Coupon one use.. and with my prime member of 15 thats 55%
No, it is not. You cannot just add the individual discounts like that and then subtract the lot; they need to be applied one after the other. For example: Say you have a total of 100 USD without any discount applied, then the calculation would be as follows:
100 USD
- 40 USD (40% of 100 USD for the Welcome Coupon)
= 60 USD
- 9 USD (15% of 60 USD for Prime)
= 51 USD (and not 45 USD if you deducted 55% of 100 USD)
Changing the order the discounts are applied does not change the final total:
100 USD
- 15 USD (15% of 100 USD for Prime)
= 85 USD
- 34 USD (40% of 85 USD for the Welcome Coupon)
= 51 USD
BTW: If you click on the little down-arrow next to "Discount" under "Subtotal" of the order page, you will see what amounts were deducted for what type of discount.
Also:
- You should consider removing the Welcome Discount since you already get 40% discount for the "Buy 2 get 40% off" promo for May and perhaps save the Welcome Discount for later.
- AFAIK only the Prime discount is applied on top of (or rather AFTER) other discounts. It is also important to realize that the (non-Prime) discounts apply only to the list prices, meaning that if there is an item that is already 20% off, a 40% discount will not apply to the new price after the 20% discount but only to the original list price (the deduction is of course still higher than 20%, but it is not 20%+40% as one might think).