11 to 12 year olds

Discounts in the stores -The shirt I wanted to buy for my friend’s birthday last week had a 15% discount, so it costs me 11,900 colones. This week there is also another shirt for sale that I liked and it had a 35% discount. However, I have noticed that the original price (without discount) of that new shirt was 5,000 colones more expensive than the original price of the shirt I saw last week.

Which of the two shirts costs less? Why?

Taken from: https://pasemosunrato.compematic.com/​