You can solve mysteries with math, and you can do it in either English or Spanish, with One Minute Mysteries – Misterios de un Minuto: Short Mysteries You Solve With Math! – ¡Misterios Cortos que Resuelves con Matemáticas!, by Yoder and Yoder.
The original version of this book was all English, and was a best seller. This new version obviously gives you mucho mucho mas and math to boot.
The One Minute Mysteries series is well known and widely loved, and is recommended by the NSTA.
Have a notebook or a pile of blank paper and some writing instruments handy because you will need them to work out some of these problems.
This is for kids age 10-14, and is a well written, well constructed, well printed resource. I strongly recommend it if your family has young ones around that age, regardless of their math level. Also check out One Minute Mysteries: 65 Short Mysteries You Solve With Science! and One-Minute Mysteries and Brain Teasers: Good Clean Puzzles for Kids of All Ages.