` a) ` ` 4.(x - 3) = 7^{2} - 1^{2020} `
` => 4x - 12 = 49 - 1 `
` => 4x - 12 = 48 `
` => 4x = 60 `
` => x = 15 `
` b) ` ` 2^{x} + 1 . 2^{2019} = 2^{2020} `
` => 2^{x} + 1 = 2 `
` => 2^{x} = 1 `
` => x = 0 `
` c) ` ` 3^{2}.(x+4) - 5^{2} = 5^{2} . 2^{2} `
` => 9(x + 4) - 25 = 100 `
` => 9x + 36 = 125 `
` => 9x = 88 `
` => x = 88/9 `
` d) ` ` 13x - 3^{2}x = 2023^{1} + 1^{2020} `
` => 13x - 9x = 2023 + 1 `
` => 4x = 2024 `
` => x = 506 `