Answer:
140 degrees
Step-by-step explanation:
Due to ∠3 and ∠4 being vertical angles (they are across from one another) their measures are the same, therefore:
⇒ m∠3=m∠4
and since their measures are given in terms of x to find x just substitute:
⇒ x+30=2x-80 ⇒ x=110
We substitute x in m∠3=x+30 and find that m∠3=140 degrees
