g1=PathGraph[Range[15],
DirectedEdges->True,
VertexLabels->Automatic,
VertexCoordinates->Thread[{Range[15],0}]]
g2=Graph[{3,4,6,9,13,14},{3->14,4->13,6->9},
GraphLayout->"LinearEmbedding",
VertexCoordinates->{{3,0},{4,0},{6,0},{9,0},{13,0},{14,0}}]
Show[g1, g2] /. {Arrowheads[x_] -> Arrowheads[.02], Arrow[x_] -> {Arrowheads[.02], Arrow[x]}}
