If x = 10, which lines are parallel? Check all that apply.

b||c; c||d; b||d

Step-by-step explanation:

Substituting 10 for x, in the angle beside b we have

7 (10) - 5 = 70-5 = 65

In the angle beside c we have

10 (10) + 15 = 100+15 = 115

In the angle beside d we have

12 (10) - 5 = 120-5 = 115

In the angle beside we have

8 (10) - 25 = 80-25 = 55

The angle beside c has a vertical angle on the other side of c. This angle would be same-side interior angles with the angle beside b; this is because they are inside the block of lines made by b and c and on the same side of a, the transversal. These two angles are supplementary; this is because 65+115 = 180. Since these angles are supplementary, this means that b||c.

The angle beside c and the angle beside d would be alternate interior angles; this is because they are inside the block of lines made by c and d and on opposite sides of the transversal. These two angles are congruent; this means that c||d.

Since b||c and c||d, by the transitive property, b||d.