Answer:
He was paid $400 commission
He is paid 2% commission on all of his sales
Explanation:
He makes a flat rate of $800
He was paid $1,200, so he made $400 commission on $20,000
($1,200 - $800 = $400)
Divide $400 by $20,000 to determine his commission rate...
$400/$20,000 = 0.02
0.02 is 2%