Bonjour j'ai besoin d'aide pour cet exercice en maths. 0.8x+2y÷3=2. 6x+5y=15. b) 4x +3y=11 3x+4=2y

a) 0.8x + 2y / 3 = 2
6x + 5y= 15

0.8x +2/3y = 2
8/10x =  2 -2/3y
x = 2*10/8 - 2/3y*10/8
x = 20/8 - 20/24 y
x = 5/2 - 5/6y

donc
6x+5y =15
6 (5/2 -5/6y) =15
30/2 -5y = 15
15 - 5 y =15
-5y = 15-15
 y = 0 /-5
y = 0

si y = 0
alors 0.8x +2/3y =2
0.8x +2/3*0 y=2
0.8x + 0 = 2
8/10 x =2
x = 2*10/8
x =20/8
x = 5/2


b) 4x = 3y =11
   3x +4 = 2y

4x = 3y -11
x = 3/4y -11/4

3x +4 = 2y
3(3/4y-11/4) +4 =2y
9/4 y -33/4 +4 -2y =0
9/4y -2y = 33/4 -4
9/4y -8/4y = 33/4 -16/4
1/4 y = 17/4
y = 17/4 * 4
y = 17


3x +4 = 2y
3x +4 = 2*17
3x = 34 -4
3x = 30
x =30/3
x =10