Answer is 20.25 angle 1
Step by step
Angle 1 and angle 3 are vertical angles, they are congruent /the same/ equal.
Angle 1 = 7x + 8
Angle 3 = 3x + 15
So our equation is
7x + 8 = 3x + 15
Solve for x
Subtract 3x from both sides to combine variables
7x - 3x + 8 = 3x - 3x + 15
4x + 8 = 15
Now subtract 8 from both sides to isolate x
4x + 8 - 8 = 15 - 8
4x = 7
Divide both sides by 4 to solve for x
4/4 x = 7/4
x = 1.75
Now to answer the question
What is the value of angle 1?
Angle 1 is 7x + 8
Substitute 1.75 for x in the equation
(7)(1.75) + 8 = angle 1
20.25 = angle 1
Check your work and do the same for Angle 3
3x + 15
Substitute 1.75 for x
(3)(1.75) + 15 = angle 3
20.25 for angle 3
