Figure F is a scale image of figure E as shown. Enter the scale factor applied to figure E to produce figure F.

Step-by-step explanation:
that means that there is one scale factor for all sides of the triangles.
so,
2 × f = 14
f = 14/2 = 7
and to control, this has to work also for the other given side :
3 × 7 = 21
correct.
so, the scaling factor to get from E to F is 7.