Answer
You have to take $9$ mg.
Work Step by Step
RECALL:
$P=BR$ where $B$=base, $P$=part, and $R$= rate or percent
The given problem has:
$B=60$ mg
$R=15\%$
Solve for $P$ using the formula above to obtain:
$P=BR
\\P=15\% \times 60
\\P=0.15 \times 60
\\P=9 \text{ mg}$
Thus, you have to take $9$ mg.
