Answer:
100 - 20 = 80 Length Of the Garden
Step-by-step explanation:
So You Can do 20 Ft Minus 100 Because 100 is the Total so Heres a Graph To Show You
Total= 100 Ft
Width= 20
Length=?
Total - Width = Length
100 - 20 = 80 Length Of the Garden
The 4th selection is appropriate.
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Desmos.com has a wonderful graphing calculator. They also have apps for Android and iOS phones and tablets. Of course, your TI-83/84 or equivalent will do this, too.