9 I think, soo sorry if i'm wrong...
Because of rules of geometry we know that a+b=180 degrees so we can add the equations together and set that equal to 180 and solve
6x-48+4x+38=180
subtract 38 from both sides and add 48 to both sides
then add like terms
10x=170
and divide by 10 to get
x=17
The best answer to go with is b you’re welcome have a great day