Here’s a picture of my work. The answer is seven. Hope this helps :-)
Is it SV squared? Or times 2

Point-slope form is
, where
is the slope and
is a point on the line.
Substitute in the values. 
Simplify the negative subtraction to addition. 
Answer:
<u>The difference in areas:</u>
- 124 - 34 = 90 square feet
<u>Percent increase:</u>
6/x-3=3/x
3x-9=6x
3x=-9
x=-3
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