Question 252905
Since she got 10% off she paid 90%
Since she got 15% off she paid 85%
Notice that contrary to some myths it makes no difference which percent is taken first but she does get less than 25% 
You can't just add the 10 and 25 to get 25%

If they were specific dollars amounts it does matter which is first
From a math standpoint, why doesn't the order matter? 
What is the property about order of multiplication (and addition) ?
Commutative - Surely you remember that! -lol
.85(.90x)=306
x=400 dollars 
first she got 10%=40
which brought it down to 360
then 15% more= 54 more
85% *360=306
.85*.90=.765
She paid 76.5 percent not 75 %