# Track Wei : Week 3

**Published by:** [lizgeorge](https://paragraph.com/@lizgeorge/)
**Published on:** 2023-02-24
**URL:** https://paragraph.com/@lizgeorge/track-wei-week-3

## Content

EIF Fellowship challenges for the week :Challenge : Build a Dex The challenge was to build a simple decentralized exchange with one token pair (ERC20 and ETH). It helped to understand the concept of Reserves , Automated Market Makers (AMM) where reserves will provide liquidity to swap between the tokens. Tutorial also helped to explore into the Constant formulae (x * y = K) used in Uniswap v2. x * y = k, Where x and y are the balance of the assets in the pool. Given Δx (Input value), to swap Δx for Δy, Uniswap V2 will perform the following calculation: ** (x + Δx ) * (y + Δy) = k** ** Δy = y - k/(x + Δx )** We wrote two functions for swapping from each asset to other, ethToToken() and tokenToEth(). Deployed App : DEX Contract Verified contract address : ContractChallenge : State Channel Application State channels is a scaling solution in cases where a fixed set of participants want to exchange value-for-service at high frequency. For the challenge, the service provider is a Guru who provides wisdom to each client Rube through a one-way chat box. Each character of text that is delivered is expected to be compensated with a payment in ETH. The Guru provides the service in exchange for signed vouchers which can later be redeemed on-chain. The challenge helped in understanding the signature and its onchain verification using ecrecover function.Deployed App : State Channel Application Verified contract address : Contract

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