X/9 - 15
X divided ( / ) by 9 minus ( - ) 9
3 to the power of 1 simplified, is just 3.
Example: 
We can see that there is more than one number with the variable x, therefore, we say they're ''like terms'' and because of that they can be summed. We do this with all of the other numbers with similar variables. If no numbers with similar variables are left, like 4a, you don't do anything but write them as they are. You can also see that 8 and 9 can also be summed because neither of them has a variable, therefore they're similar.
In this step, you just do the operation with the numbers and keep the same variable.


since there are not more numbers similar in variables, this operation is done.

Step-by-step explanation:
hope it's help.
see answer attached
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.

You will cross multiple.

you will divide 42000 by 560


The complete answer will be: The patient took 75% of the 560mg dose of medication.