(3x + 5)(4x − 1) = (6x − 3)(2x + 7)
$12x^2 + 20x - 3x - 5 = 12x^2 - 6x + 42x - 21$
17x − 5 = 36x − 21
17x − 36x = −21 + 5
−19x = −16
$x = \frac{16}{19}$

(5x − 1)(2 − x) = (x − 3)(2 − 5x)
$10x - 5x^2 - 2 + x = 2x - 6 - 5x^2 + 15x$
11x − 2 = 17x − 6
11x − 17x = −6 + 2
−6x = −4
$x = \frac{4}{6} = \frac{2}{3}$

(5x + 1)(2x − 3) = (10x − 3)(x + 1)
$10x^2 + 2x - 15x - 3 = 10x^2 - 3x + 10x - 3$
−13x − 3 = 7x − 3
−13x − 7x = −3 + 3
−20x = 0
x = 0

(7x − 1)(x + 5) = (3 + 7x)(x + 3)
$7x^2 - x + 35x - 5 = 3x + 7x^x + 9 + 21x$
34x − 5 = 24x + 9
34x − 24x = 9 + 5
10x = 14
x = 1,4