Answer:
b||c; c||d; b||d
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.