At 27:20 I have to guess the row since i don't wanna think so i took the row as [x,y,z] and then solve it manually to find that x+z = -3 will solve it. I thought i am so smart but........At 37:40 I couldn't solve it using taking the variables although matrix P was an easy one to think but at time of lecture it seems hard but i guess it comes through practice####[['[x,y,z] ', 'Mathematical_Related_Concept', 'NEU'], [' x+z = -3 ', 'Mathematical_Related_Concept', 'NEU']]