The first figure has 3 line segments.
the second figure has 3+3 =3*2 = 6 line segments
the third figure has 3+3+3 = 3*3 = 9 line segments
the fourth figure has 3+3+3+3=3*4=12 line segments...
so it is clear that:
the 20th figure has 3*20=60 line segments.
Answer: 60