Answer:
He must sell $14000 of merchandise
Explanation:
The salesperson earns a base salary of $800
This means that he must make
$3600 - $800 = $2800 worth of commisions
Let x, be the value of the mechandise that he needs to sell.
This means that
x*0.20 = $2800
x = $2800/0.20
x = $14000
He must sell $14000 of merchandise