Answer:
a) 
 or 250 * 0.12.
 or 250 * 0.12.
b) 30 photos.
Explanation:
Given : Olaf has 250 files saved on an external hard drive. Of those files, 12% are photos. 
To find : (a)Write a percent equation to find the number of files that are photos. (b) How many photos does Olaf have saved on his external hard drive.
Solution : We have given total files = 250 .
 12% are photos. 
a) Percent equation of number of files that are photos = 
 .
.
⇒ 250 * 0.12 
b) Total photos in files = 250 * 0.12 = 30 .
Therefore, a) 
 or 250 * 0.12.
 or 250 * 0.12.
b) 30 photos.