C. 5/2.
You can get the scale factor by putting the measurements of similar sides on a fraction,
In this case 20/8 =5/2, 10/4 = 5/2
Answer: 7,-7
Step-by-step explanation: 7 squared is 7 times 7 which equals 49
-7 times -7 is also 49 bc the negatives cancel each other out