Answer:
A: 15
Step-by-step explanation:
The angles are opposite to each other.
Vertically opposite angles are equal in size.
Put up an equation and solve for a.
6a + 10 = 3a + 55
Subtract 3a and 10 on both sides.
6a - 3a = 55 - 10
Combining like terms.
3a = 45
Divide both sides by 3.
a = 45/3
a = 15
The value of a is 15.
