1° Je dois developper ( 5x - 9 ) ( 2x + 1 ) - 4 ( x - 3 ) 2° Je dois calculer  5/6 + 7/8 x 1/3 - 1/16 : 3/8

1° Je dois developper ( 5x - 9 ) ( 2x + 1 ) - 4 ( x - 3 )  
=10x²-18x+5x-9-4x+12
=10x²-17x+3

2° Je dois calculer  5/6 + 7/8 x 1/3 - 1/16 : 3/8
=5/6+7/24-8/48
=20/24+7/24-4/24
=23/24

1)
(5x - 9)(2x + 1) - 4(x - 3)
5x x 2x + 5x x 1 - 9 x 2x - 9 x 1 - 4 x (x) - 4 x (-3)
10x² + 5x - 18x - 9 - 4x + 12
10x² - 17x + 3

2)
5/6 + 7/8 x 1/3 - 1/16 : 3/8
5/6 + 7/24 - 1/16 x 8/3
5/6 + 7/24 - 1/6
20/24 + 7/24 - 4/24
23/24

J'espère t'avoir aidé(e)! :)