Answer:

Kelly is correct.
Step-by-step explanation:
One person is able to plant 4 trees
Let x be the number of people
y be the number of trees
The situation is represented by

5 people are able to plant 20 trees

So, the situation is represented by 
Hence, Kelly is correct.
8-9n=15 I believe
At least I hope
Here is all the work with it
The area of square is
square units
<h3><u>Solution:</u></h3>
Given that square has side length (x+5) units
To find: area of square
<em><u>The area of square is given as:</u></em>

Where "a" is the length of side
From question, length of each side "a" = x + 5 units
Substituting the value in above formula,



Thus the area of square is
square units