72 s

t_1

t_1+t_2=2t_1+r

t_1+t_2+t_3=3t_1+3r

r = 11 (slider from 1 to 30, step 5)
A = Point(xAxis)
C: ((3 * abs(A)) + (3 * r), 0)
A': (abs(A), 1)
B: ((2 * abs(A)) + r, 0)
B': (abs(B), 1)
C': (abs(C), 1)
O: (0, 0)
f = Segment(O, A')
g = Segment(A, B')
h = Segment(B, C')
i = Segment(O, C')
D = Intersect(g, i)
E: (abs(D), 0)
j = Segment(E, D)