Answer: It's 48%. See below. 
Explanation:
By definition, percent means out of a hundred. For instance, 10 percent is 10 out of 100. 
One way to make 
 a percent is by making the denominator 100. In order to do so, multiply the numerator and the denominator by 4, since 25 times 4 is 100. 
 = 
 = 48 %
This is very simple, and mental math is definitely possible. Hope this help.