Excess delivery

Sir it says in the textbook “If the seller delivers more than was ordered, the buyer may take delivery of some or all of the excess, or
not, as they choose: Article 52. If they do accept additional goods however, they must pay for them at the
contract price.”

For example contract price is $100 for 10 goods, so $10 each.

So if they accept 5 additional goods, does it mean they still pay the price written in contract as the $10 each, so they pay 15 x $10 = $150

or they still pay $100?

Thanks sir