Answer:
Explanation:
Let's start by using algebra to solve the problem. 
Let x be the number of games that Mark started with. 
Mark sold half of his games to his brother, so he sold x/2 games. This means he had x - x/2 = x/2 games after selling half to his brother.
He then bought 16 more games, so he had x/2 + 16 games.
Finally, we're told he now has 36 games, so we can set up the equation: 
x/2 + 16 = 36 
Simplifying the equation, we get: 
x/2 = 20 
Multiplying both sides by 2, we get: 
x = 40 
Therefore, Mark started with 40 games.