Given is -
The variables y and x have a proportional relationship, and y = 5 when x = 4.
[tex]\frac{y}{x}=\frac{5}{4}[/tex]
As we have to find the value of x when y= 8 so putting y = 8 in the above relationship, we get :
[tex]\frac{8}{x}=\frac{5}{4}[/tex]
[tex]5x=32[/tex]
[tex]x=6.4[/tex]
Hence, the answer is 6.4
