By using two arbitrary points on the line, we can find the slope using the slope formula:

We'll use the points (0, 4) and (5, 1) for this.
1 - 4 / 5 - 0
-3 / 5
The slope of the line is -3/5.
20% decrease should be the answer
Answer:
16 units
Step-by-step explanation:
The perimeter is the sum of the lengths
Add up the lengths as shown
3+2+1+2+3+1+1+3
16 units