Answer: The lines are skew.
Step-by-step explanation: Two lines can only be parallel OR skew Or intersect each other. To determine that:
1) If the lines are parallel, divide the coefficient that precedes the variable of each equation and compare:
[tex]\frac{7}{8} \neq \frac{6}{8} \neq \frac{1}{4}[/tex]
Since they are not equal, L1 and L2 are not parallel.
2) If the lines intersect, when you equal the equations the variable is a valid statement:
25 + 7t = - 12 + 8t (1)
17 + 6t = - 17 + 8t (2)
t = - 11 + 4t (3)
Using (3) to solve the system:
t - 4t = - 11
3t = 11
t = [tex]\frac{11}{3}[/tex]
Substituing t in (1):
25 + 7(11/3) = -12 + 8(11/3)
25 + 77/3 = - 12 + 88/3
[tex]\frac{152}{3} = \frac{52}{3}[/tex]
Which is not true, so, the lines does NOT intersect.
As they are none of the other options, it can be concluded that the lines L1 and L2 are skew.