Answer:
A. 15
Step-by-step explanation:
The angles are vertical angles, therefore they are congruent. We can set the two measures equal to each other.
[tex]6a+10=3a+55[/tex]
Now, solve for a. We must get a by itself on one side of the equation.
First, subtract 3a from both sides of the equation.
[tex]6a-3a+10=3a-3a+55[/tex]
[tex](6a-3a)+10=55[/tex]
[tex]3a+10=55[/tex]
Next, subtraction 10 to both sides of the equation. We subtract because 10 is being added to 3a. The inverse of addition is subtraction.
[tex]3a+10-10=55-10[/tex]
[tex]3a=55-10[/tex]
[tex]3a=45[/tex]
3 and a are being multiplied. The inverse of multiplication is division. Divide both sides of the equation by 3
[tex]3a/3=45/3[/tex]
[tex]a=45/3[/tex]
[tex]a=15[/tex]
The value of a is 15 and choice A is correct.
