Answer:
∠a = 10°
Explanation:
The measure of ∠a = x
The measure of ∠b = 4x-30
It is also mentioned that the measure a and measure b are vertical angles. We need to find the value of a.
For vertically opposite angles,
∠a = ∠b
x = 4x-30
or
4x-30=x
Taking like terms together,
4x-x= 30
3x = 30
x = 10
So, the meausre of ∠a is equal to 10°.