27900 - __ = 22500 i don't get this question plz

27900-5400=22500 because 27900-22500=5400

Your trying to solve what number can we subtract from 27,900 to get 22,500. A trick is to rewrite the question and line it up. Start by putting x into the space for the umber we are looking for.Looks like this:
27,900-x = 22500. Isolate the x value by subtracting 22,500 to 27,900 and adding x to the other side: 27,900-22,500 = x Line up the two number and you'll get your
 27,900
-22,500 
   5,400 = x

The discount is 8.70 . you dont tell us the percent of tax added so there is no way to find out, unless i'm not seeing anything. without tax its 37.70