the equation would be x-12=20.
the solution would be x=8.
Answer:
B
Step-by-step explanation:
As I've shown on picture that I attached:
∠ADC=∠ADB+∠BDC⇒134=5x+4+7x-2
12x+2=134
12x=132⇒x=132/12
x=11
Angle BDC measure 7x-2=7*11-2⇒∠BDC=75.
Answer: proof below
<u>Step-by-step explanation:</u>
Use the Difference formula for sin:
sin (A - B) = sin(A)·cos(B) - cos(A)·sin(B)
sin (180° - θ) = sin(180°)·cos(θ) - cos(180°)·sin(θ)
= 0 · cos(θ) - -1 · sin(θ)
= 0 - -sin(θ)
= + sin(θ)
sin (180° - θ) = sin(θ) 
5(x+3)=7x-3 which is the equation, then we solve for it, and the answer is 9