问题
I want to get the total amount with the help of Final amount and Discount rate.
For Example.
Grand total = 100
Discount = 15%
Final Amount =100*.15=85
if I have only two variables
Final amount = 85
Discount = 15%
Grand total = ?
Now I can get back Grand total with the help of "Final Amount" and "Discount rate"?
回答1:
Let Grand Total = X
X-(X * 15 %) = 85 then if you find the value of X then your Grand total can e found.
X - 3X/20 = 85
17X= 85*20
X = (85/17)*20
X =100
Put it .. You will find the Grand Total
回答2:
Let x = Grand Total.
We know that
100-100*0.15=85
Let's substitute 100 with X.
x-(x*0.15) = 85
then we can simply apply basic PEMDAS operation. So let's multiply
x-0.15x = 85
we know that the first x is = 1, so
1x-0.15x = 85
which equals to
0.65x=85
divide 0.65 on both sides to find X
0.65x/0.65 = 85/0.65 = 100
来源：https://stackoverflow.com/questions/16561287/how-to-get-the-actual-value-after-subtracting-discount