28x? - 19x = 20
x? - 19/56x = 5/7 + (- 19/56)?
x? - 19/56x = (2,240 + 361)/3,136
(x - 19/56)? = 2,601/3,136
x - 19/56 = ? 51/56
= x - 19/56 - 51/56, = x - 70/56, = x - 5/4, = 4x - 5
= x - 19/56 + 51/56, = x + 32/56, = x + 4/7, = 7x + 4
Answer: (4x - 5)(7x + 4)