Given:
one capsule is 20mg.
Piroxicam 20mg capsules take 1 capsule 2 times a day.
[tex]\text{for one day =20}\times2=40[/tex]That means 40mg capsule in a day.
For 90 days ,
[tex]\begin{gathered} C=40\times90 \\ =3600\text{ mg} \end{gathered}[/tex]Answer: Marilyn will take 3600 mg peroxicam capsule in 90 days.