You can put this solution on YOUR website!
You're traveling 25mph.
Increase that (or multiply that) by 11%, or (.11)
That gives you 25 x .11 = 2.75
Since you increased your speed by 11%, add 2.75 to your original speed:
25 + 2.75 = 27.75
So you are now traveling 27.75 mph, rounded up, you're going 28mph.
Hope this helps!