How inanly gins of $)$ should be added to the following formula to make it isotonic?

Ephedrine $)=(0\mathrm{.}17$

Water to $50ml$

$0\mathrm{.}39$

$0\mathrm{.}2339$

$0\mathrm{.}109g$

$0\mathrm{.}1559$