Answer
Find out the what is the value of x when y = 8 .
To prove
As given
The variables y and x have a proportional relationship.
y = kx
Where k is the constant of proportionality.
As y = 5 when x = 4
Put in the above
5 = 4k
Now find out the value of x , when y = 8
x= 6.5
Therefore when y = 8 than x = 6.4