Решим уравнения по порядку:
1) 3x = 36 - x
$$3x = 36 - x$$
$$3x + x = 36$$
$$4x = 36$$
$$x = rac{36}{4}$$
$$x = 9$$
Ответ: 9
2) 13x + 24 = 9x
$$13x + 24 = 9x$$
$$13x - 9x = -24$$
$$4x = -24$$
$$x = rac{-24}{4}$$
$$x = -6$$
Ответ: -6
3) 8x + 5 = 5x + 29
$$8x + 5 = 5x + 29$$
$$8x - 5x = 29 - 5$$
$$3x = 24$$
$$x = rac{24}{3}$$
$$x = 8$$
Ответ: 8
4) 7x - 4 = 4x + 17
$$7x - 4 = 4x + 17$$
$$7x - 4x = 17 + 4$$
$$3x = 21$$
$$x = rac{21}{3}$$
$$x = 7$$
Ответ: 7
5) x + 2 = 5x + 18
$$x + 2 = 5x + 18$$
$$x - 5x = 18 - 2$$
$$-4x = 16$$
$$x = rac{16}{-4}$$
$$x = -4$$
Ответ: -4
6) 7 - 4x = 2x - 23
$$7 - 4x = 2x - 23$$
$$-4x - 2x = -23 - 7$$
$$-6x = -30$$
$$x = rac{-30}{-6}$$
$$x = 5$$
Ответ: 5