`(x + 1)/2020 + (x + 2)/2019 = (x - 1)/2023 + (x - 2)/2022`
`⇒ (x + 1)/2020 + 1 + (x + 2)/2019 + 1= (x - 1)/2023 + 1 + (x - 2)/2022 + 1`
`⇒ (x + 2021)/2020 + (x + 2021)/2019 = (x + 2021)/2023 + (x + 2021)/2022`
`⇒ (x + 2021)/2020 + (x + 2021)/2019 - (x + 2021)/2023 - (x + 2021)/2022 = 0`
`⇒ (x + 2021)(1/2020 + 1/2019 - 1/2023 - 1/2022) = 0`
Ta thấy `(1/2020 + 1/2019 - 1/2023 - 1/2022) \ne 0`
`⇒ x + 2021 = 0 ⇒ x = -2021`
