Respuesta :

Step-by-step explanation:

8.4 is the ans

4x+8y=40

4x + 6.4=40

4x=40-6.4

4x=33.6

x=33.6÷4

x=8.4

Answer:

4x+8y=40

4x+(8+0.8)=40

4x+6.4=40

4x+6.4-6.4 =40-6.4

4x=33.6

4x÷4=33.6÷4

X=8.4