reading compherension - Tesco document

[shahar]

In the link: https://www.tesco.com/groceries/en-GB/zone/general-terms-and-conditions
this text is written:
For example, to use a ₤3 off ₤30 coupon a ₤5 off ₤50 coupon in the same transaction (assuming that these coupons can be used together), you must spend at least ₤80.
What is the meaning of underlined text?
What is the meaning of the whole text?
2. Other things that is off-topic:
"When you use a coupon, you warrant to Tesco that you are the duly authorised recipient of the coupon and that you are using it in good faith."
In the link after (g.) seucrity and Fraud subtitle section after Coupon Terms and Conditions title section,
a. What is the meaning of underlined text?
b. What is duly in this context?

 

[Otis]

₤3 off ₤30 coupon

If the total purchase of eligible items is ₤30 or more, then the coupon is worth ₤3.

EG: If the eligible purchase is exactly ₤30, then you pay ₤27 with the coupon (10% savings). If the purchase is more than ₤30, the coupon is still worth ₤3 (savings less than 10%).

The whole text means that your savings will be ₤8, if the purchase is ₤80 or more, whenever you're allowed to use both coupons together.

Note also the section describing the order in which coupons, discounts and promotions are applied, when multiple offers are used in the same purchase.

duly authorised recipient

Duly is an adverb. It means 'properly', 'regularly' or 'officially'.

The whole text is a warning. When Tesco offers deals to customers or employees, then those are the only people authorized to use those deals. Basically, it's a legal condition to prevent scams against the company or people.