Adding and subtracting fractions. HASSAN:I bet this was a temple. OLIVIA:And this was a massive pillar. HASSAN:Does this go together with this? OLIVIA:Hmm, not sure. HYPATIA:Sorry it's a bit of a ...

Adding and subtracting using written methods. OLIVIA: Wow, what is this place? HYPATIA: The Cosmic Library is filled with many wonders, but to open its portal you'll have to solve this puzzle ...