A and B are vertical angles with mA= x and mB= 4x - 30. What is mA?
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Find the value of X in triangles by subtracting known angle measurements from 180 degrees. Since the value of all angles within a triangle must equal 180 degrees, if you know at least two angles, you can subtract them from 180 to find the missing third angle.

Facts About Vertical Angles- Vertical angles are always congruent that are of equal measure. Both pairs of vertical angles (four angles altogether) always sum up to 360 degrees. Angles from each pair of vertical angles are known as adjacent angles and are supplementary (the angles sum up to 180 degrees).

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  10°

Step-by-step explanation:

Vertical angles have the same measure, so ...

  ∠A = ∠B

  x = 4x -30

  30 = 3x . . . . . . . add 30-x to both sides

  10 = x = ∠A . . . . divide by 3

The measure of ∠A is 10°.

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step-by-step explanation:

answ9x x 3=

step-by-step explanation: