Answer:
800 mL
Step-by-step explanation:
Let's say we add [tex]x[/tex] mL of methyl alcohol to the water.
Then the proportion of methyl alcohol in the solution would be [tex]\frac{x}{200+x}[/tex].
So we have
[tex]\frac{x}{x+200}=0.8\\\\x=0.8x+160\\\\0.2x=160\\\\x=800[/tex]