You need to set the correct porportion. x is the percent value you want to find. 100 is the maximum percentage. 420mg is what was taken out of the maximum 560mg dose.
[tex] \frac{x}{100} \times \frac{420}{560} [/tex]
You will cross multiple.
[tex]560x = 42000[/tex]
you will divide 42000 by 560
[tex] \frac{560x}{560} = \frac{42000}{560} [/tex]
[tex]x = 75[/tex]
The complete answer will be: The patient took 75% of the 560mg dose of medication.
