Answer:
Mary has 16 video games. 
Explanation:
Let John be 
 and Mary be
 and Mary be 

Equation: 

Combine like terms: 

Subtract 2 from both sides: 

Divide both sides by 2: 


Hold up!
In the beginning, we set 
 as John, and
 as John, and 
 as Mary. The question asks for Mary, so
 as Mary. The question asks for Mary, so 
 .
. 
Let's check our work: 

Replace 
 for 14...
 for 14...



Hope this helped! :)