If shown,
AB
and
CD
are straight lines. Find x in each case.
WILL MARK BRAINLISIT

Answer:
x=60
Step-by-step explanation:
here DOB and AOC are vertically opposite angles and the values of them are equal. so lets take the two angles as y.
x+DOB is 90(because EOA is 90 and the sum of angles in a straight line is 180), DOB is y and can write a equation as x+y=90
and 30+2x+y = 180 ,
2x+y=150, (180-30)
then two equations can be made.
x+y=90
2x+y=150
simplifying these two simultaneous equations
can get x as 60. and 2x is 120.