The first thing we must do for this case is to calculate the scale factor.
For this, we make the relationship between two parallel sides.
We have then:

Substituting values we have:

We are now looking for the value of AB
We have then:

Substituting values:

Answer:
The scale factor is:

The value of AB is:

Answer:
The mean is 0.65
Step-by-step explanation:
See the attachment for step by step solution and interpretation.
Answer:
1. x= 20/3 or 6.6666 repeating
2. x=3
3. a=39
Step-by-step explanation:
1. subtract 25 by 5 to get 20, then divide 20 by 3 to get x
2. divide 7 by 21 to get x
3. add 8 to 31 to get a equals 39