Explanation:
135+k=180(sum of angles on a straight line)
k=180-135
k=45
so now u can use k to solve for x
k+9x is also on a straight line
so k+9x=180
we know k so substitute the value in the equation
45+9x=180
9x=180-45
9x=135
cancel 9 will divide 135 15 times
therefore x=15 degrees