Answer:
The scale factor is equal to 2
Explanation:
we know that
If two figures are similar, then the ratio of its areas is equal to the scale factor squared
Let
z ----> the scale factor
x ----> the area of polygon d
y ---> the area of polygon c
so
![z^(2)=(x)/(y)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/fyxpe52kf1pqj0udxbjxxf82qpn4fb4w0e.png)
we have
![x=28\ units\^(2)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/ptzv0eaakp9n7rvh3n68sgtipc59nshs5v.png)
![y=7\ units\^(2)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/djkxkx3kb9yqyt8lczr8xb5h9zxt9x873k.png)
![z^(2)=(28)/(7)](https://img.qammunity.org/2019/formulas/mathematics/middle-school/dpi7scstpnbsayb47ostb921myqg2w7mkr.png)
![z^(2)=4](https://img.qammunity.org/2019/formulas/mathematics/middle-school/foape578wp9bbilqqdih84zel6xjjnx741.png)
![z=2](https://img.qammunity.org/2019/formulas/mathematics/high-school/5m8pq9sb0mw2b2i10swjba0sqvrwrlzn24.png)
therefore
The scale factor is equal to 2