Question

how to construct 75 degrees angle with ruler and compass?

Answer 1

first make a 60 degree angle.
then make a 120 degree angle.
make a 90 degree angle from 60 degree and 120 degree.
then from 90 and 60 make the 75 degree angle.
thats all......

Answer 2

Construct 60 degrees angle 
construct 120 degrees angle 
bisect 60 and 120 degrees angles
then 90 degrees angle was formed
then bisect 90 &60 degrees angle
and the result is 75 degrees angle