Answer:
Scale factor: 1.85714285714 or 1.86 (if rounded up)
Explanation:
Since the lengths of the triangles are corresponding, you need to count how many lines each triangle measures to.
The small triangle is measured to 7 lines.
The bigger triangle is measured to 13 lines.
13/7 = 1.85714285714 but if rounded up, it's 1.86.