A person spent $190.Everyone got a coupon by spending $50. So a person could get another coupon if he had spent $10 more. The conversation between the customer and the shopkeeper went this way:
Shopkeeper: Sorry Sir, you could get another coupon if you had spent $10 more.
Person: But I spent only $10 less.
Is the use of "less" And "more" natural? And in these sentences can "dollars" be dropped? Like:
You could get another coupon if you had spent 10 more.