the second option is more profitable
if she sells more than $ 18000 per month
Step-by-step explanation
Step 1
let's check the options we have
a)
one paying $3,000 per month
it means, in a month , she will receive 3.000

b)$2,100 per month plus a 5% commission on all sales made during the month
if x represents the sales, then the formula would be

Step 2
now, to make the option 2 more profitable

solve for x

therefore, the second option is more profitable
if she sells more than $ 18000 per month
I hope this helps you