Finally bought my textbooks! XD
A way to get discounts for triple science/double math students: Buy all books excluding English at Popular. Use your Popular student card for the 5% discount. It will total $203 +. You'll get ten stickers ( their promotion thing )that will entitle you a $5 Popular voucher that is immediately use-able. After which you can buy your English books at the school bookshop. The English books cost $28.80. In total, everything will add up to approx. $230. It's cheaper than buying all your books at the school bookshop. It'll total $256.15 then.
See, you'll save $20!