The red bathing suit cost: $25 - the discount of $7
The blue bathing suit cost: $20 flat
Sandra likes the blue bathing suit more, but she doesn't have $20 to spend on a bathing suit; the red bathing suit has a discount of $7, making it $18.
The question: Why does Sandra buy the red bathing suit?
Response: Because it had a discount, making it cheaper than the blue bathing suit.
Answer:
4) Tiene descuento