Answer :

wasepo5546

Answer:

x=18

Step-by-step explanation:

(6x+3)+(3x+15)=180

(6x+3x)+(3+15)=180

9x+18=180

    -18  -18

9x=162

162/9

x=18

These two angles should sum to 180 since they form a line. So 6x+3+3x+15=180. 9x=162. x=18.