i guess i've figured it out
with some help from another forum.
lets name the starting position A and the intermediate position on 25 degree W as B.
when we join points A and B to form a triangle for calculation purpose, it divides conversion angle into two equal parts of 2.16 degress each.
now solving the sum in the same manner:
tan 2.16= X (unknown)/150
X=5.65nm
X/60 = 0 degrees 5 minutes
hence position B= 60 degrees + 5 minutes
=60 degrees 5 minutes
