Bonus task

Our marketing team have added another promotions as an incentive for our customers to purchase these items.

If you buy 3 Kids T-shirt then the third one is free.


Test data
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Basket: 003, 003
Total price expected: £39.90

Basket: 003, 003, 003
Total price expected: £39.90

Basket: 003, 003, 003, 002
Total price expected: £76.41



Bonus task
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Add another scanable product item: Discount coupon
The list of available items should be:

Product code  | Name                   | Price
----------------------------------------------------------
001           | Lavender heart         | £9.25
002           | Personalised cufflinks | £45.00
003           | Kids T-shirt           | £19.95
004           | Discount coupon        | -£5.00

Discount coupons can not be combined with other promotions


Test data
---------

Basket: 003, 003, 003, 002, 004
Total price expected: £71.41