Answer:
ratio will change.
Explanation:
There are 10 girls and 8 boys in Mr. Augello's class.
The ratio of boys and girls are = 
 
 
 = 
 
 
  = 5 : 4
Now 5 girls and 5 more boys join the class. 
so the new number of girls are 10 + 5 = 15 girls
the new number of boys are 8 + 5 = 13 boys
Now the ratio of boys and girls are = 
 
 
  = 15 : 13
Hence the ratio will change.