Answer:
8.4
Step-by-step explanation:
the equation 4x+8y -40 can be written as 4x-8y-40=0, this represents a line in a space of two dimensions.
solving for x when y=0.8 we have the equation below>
[tex]4x+8*0,8-40=0[/tex]
Which gives that x=42/5, or in more simpler terms, 8.4