--- title: The unknown on both sides of a story — a lesson of Mova's school · trees and pragmatics description: «The unknown on both sides of a story», a lesson of the lessons course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Sometimes the unknown number appears twice: 3 bags and 5 more weigh as much as 1 bag and 21 more. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/lessons/171-unknown-on-both-sides/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Lessons](https://md.mova.elamur.ai/free/en/corpora/school/lessons/) / The unknown on both sides of a story # The unknown on both sides of a story Lesson 171 of the lessons course of Mova's primary school: 3 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). - [0](https://md.mova.elamur.ai/free/en/corpora/school/lessons/171-unknown-on-both-sides/0/) — Sometimes the unknown number appears twice: 3 bags and 5 more weigh as much as 1 bag and 21 more. - [1](https://md.mova.elamur.ai/free/en/corpora/school/lessons/171-unknown-on-both-sides/1/) — Take the same from both sides, like on a balance: take 1 bag away from each side, then 5 from each side. - [2](https://md.mova.elamur.ai/free/en/corpora/school/lessons/171-unknown-on-both-sides/2/) — What is left says 2 bags = 21 - 5 = 16, so one bag is 16 / 2 = 8. - ← previous: [The dog that runs back and forth](https://md.mova.elamur.ai/free/en/corpora/school/lessons/170-the-dog-between-two-walkers/) - next →: [Working backwards through three steps](https://md.mova.elamur.ai/free/en/corpora/school/lessons/172-backwards-three-steps/) - ↑ back to [Lessons](https://md.mova.elamur.ai/free/en/corpora/school/lessons/)