Computer graphics question:- Note :- I want in depth solution for it.(There is already solution available in Chegg for them but it's isn't proper.)

1) Given two triangles P with vertices P1(4,9,5), P2(7,5,4), P3(1,3,5) and Q with vertices Q1(1,6,8), Q2(6,2,8), Q3(1,2,4), determine the visible surfaces using Z-buffer method.

2)Given two triangles P with vertices P1(100,100,50), P2(50,50,50), P3(150,50,50) and Q with vertices Q1(40,80,60), q2(70,70,50), Q3(10,75,70). Determine which triangle should be painted first using the scan-line method