Can’t wrap my head around as to why x is larger. Both x and y will be smaller than 90 degree for sure. Since it is not a right triangle, the information is pretty scarce here - how then do we know that x is larger?

Also which prep swift video should I watch to revise this concept?

Thank you.

Use the fact that the exterior angle of a triangle is equal to the sum of the two interior opposite angles. See the “Degrees of a Triangle” video on PrepSwift.

Thank you. I just re watched the video but what caught my attention is x degree is equal to the two opposite angles. That makes sense why x is larger than y! Thank you so much.