There are 5 milliliters of compound A for every 7 milliliters of compound B.
So the ration between compound A and B will be:
A:B = 5:7
Total amount of drug = 684
Therefore, the amount of drug A needed will be:
[tex] \frac{5}{5+7}*684 \\ \\
= \frac{5}{12}*684 \\ \\
=285[/tex]
Therefore, out of 684 milliliters 285 would be the compound A and the rest would be compound B