A. The relationship of <7 and <8 are that they are vertical angles, and are congruent.
B. Since vertical angles are congruent, you can form an equation where the two measurements equal each other.
C. 5y-29=3y+19 then plug y into your equation: 5*24-29=91
2y=48 and so: <7 = 180-91=89 (and since <8 is congruent)
y=24 <8 also equals 89
Your second problem:
complementary are two angles that add up to 90 degrees.
<B=x, <A=2x
2x+x=90
3x=90
x=30 so: <B=30 degrees, <A=60 degrees
Your third problem:
1. Since A and B are parallel, angle 3x+7 and angle 4x+5 are same-sided exterior angles. That means that they both add up to 180 degrees. So if you should add the two and make it equal 180
2. 3x+7+4x+5=180
7x+12=180
7x=168
x=24
3. <6 is a corresponding angle with angle 3x+7, meaning that they are congruent. So plug x into 3x+7: 3*24+7=79 and since <6 is congruent to 3x+7, <6=79 degrees
