First take a ruler and draw a line. Name this line as AB
Then make a protractor shape arc..
Now From the point the right side make a 60o angle by adjusting the radius equal to Point A to the tip of right side of the protractor shaped arc
Now taking the same radius you make 120 degree by making an arc on the protractor shaped arc.
Now as you know how to make 180 degree arc
Now from thew tip of 180 degree arc having the same radius make an Arc above the protractor shaped arc.
Now from the 120 degree ar having the same radius make an Arc above the protractor shaped arc.
Now join the midpoint to point A. It is 150 degree
Now take a radius of from 120 degree to 150 degree
Now from placing the tip of the compass on the protractor shaped arc. Now taking the radius make an arc above it. and from the 120 degree also make like this.
Now join the midpoint to point A.
Best of luck for your exams.