Question 1174140
<pre>
Let A be Anna's age
Let E be Elen's age

This part: "Anna is 12 years younger than Elen"  means
  A = E - 12  
Given Elen's age, subtract 12 to get Anna's age.  Keep in mind, Anna is the younger of the two, and this equation agrees with that.

Notice we can add 12 to both sides to get the equivalent 
  A + 12 = E  
This allows you to find Elen's age if someone gives you Anna's age.  
We can also write this as 
<b> E = A + 12 </b> 
which looks a little nicer.

If A = 25 what do you think E is?   Remember, you can use E = A + 12 ... just replace 'A' with 25...