Answer:she had 11 video games on Monday.
Explanation:
Let x represent the number of video games that Susie had initially.
On Tuesday, Susie buys three new video games from the store. This means that the total number of video games that Susie had would be x + 3
On Wednesday, she sells half of her video games in order to make extra money. This means that the number of video games that she sold is
(x + 3)/2. The number of video games left would be
x - (x + 3)/2
If she has 4 video games left after selling, it means that
x - (x + 3)/2 = 4
2x - (x + 3) = 8
2x - x - 3 = 8
x - 3 = 8
x = 8 + 3 = 11