The question is saying that x = minutes spent watching videos and y = minutes spent playing video games. Gian has 45 minutes in total to spend. The equation for Gian spending y minutes playing video games if he spent x minutes watching videos would be 45 - x, since x minutes have been taken away from Gian's 45 minutes by watching videos.
Knowing this, if he spent 5 minutes watching videos (x) on Monday, that means he spent 40 minutes playing video games. So, the first coordinate point would go to (5, 40). On Tuesday, he spent 25 minutes watching videos, which would mean he spent 20 minutes playing video games. The second coordinate point would go to (25, 20).
