Bonjour !

A= (4x -3) ( 2x-7)-5x (6 x- 4 )

8x² -28 x - 6x +21 -5 x ( 6x -4 )

8x² -28x - 6x + 21 - 30 x² + 20 x

- 22 x² - 28 x - 6x + 21 + 20 x

-22 x² - 14 x + 21

B= (8x -3) ( 7x + 6 ) - ( 8x -3) (5x-9)

(8x -3) (7x+6 -( 5x -9))

(8x -3 ) (2x +6 +9)

(8x -3) ( 2x + 15 )

C= 9 - 7 = 3 ( 2x -4 )

2= 3 ( 2x -4)

2= 6x -12

2-6x= -12

-6x = -14

x= 7/3

Bonne journée ♡