Answer:
70 [milliliters]
Step-by-step explanation:
Since the solution consists of 90% alcohol, the 63 milliliters of alcohol must represent 90% of the entire solution. Let the solution have [tex]x[/tex] milliliters in total. We have the following equation:
[tex]0.9x=63[/tex]
Divide both sides by 0.9:
[tex]x=\frac{63}{0.9}=\boxed{70}[/tex]
Therefore, there are 70 milliliters in the solution.
