Answer:
first problem) he messed up at 4(1 + 5n), only multiplying the 1 by 4, instead of both the 1 and 5n,
work-
-8n + 4(1 + 5n) = -6n - 14
-8n + 4 + 20n = -6n -14
12n + 4 = -6n - 14
18n +4 = -14
18n = -18
n= -1
second problem) he messed up towards the end, where he put 3x = 3x, then x=0. in this case, x would equal x, so the answer is "infinitely many solutions"
all the other work is correct in that problem
third problem) on the right side of the equation, ( 4x+10+3x-6), when they were adding the like numbers, instead of subtracting 6 from 10, they added 6, giving them 16 instead of 4
correct work-
2x - 8 + 3x +2 = 4x +10 + 3x -6
5x - 6 = 7x + 4
-5x -5x
-6 = 2x +4
-4 -4
-10 = 2x
-5 = x
hope i helped :)