Answer:
Myrna earned $674 for that week.
Myrna earns 2% commission IF the weekly sales is over $12,500. Since $21,200 is over $12,500. We can imply the 2% commission into Myrna's weekly pay.
Step-by-step explanation:
1) Multiply last weeks sells by .02
$21,200 * .02 = $424
2) Add $424 to Myrna's $250
$424 + $250 = 674