Step-by-step explanation:
what u suppose to do on this work, reply quickly so I can help
For this case we have that by definition, a direct variation is given by:

Where:
k: It is the constant of proportionality of the variables.
On the other hand, we have that the inverse variation is given by:

Where:
k: It is the constant of proportionality of the variables.
In this way, the correct option is: 
ANswer:
Option A
<h3>
Answer: 15 hours (choice D)</h3>
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Work Shown:
(6 hours)/(8 trees) = (x hours)/(20 trees)
6/8 = x/20
6*20 = 8*x ... cross multiply
120 = 8x
8x = 120
x = 120/8
x = 15
It takes him 15 hours to plant 20 trees.