Answer:
He would have $340 left.
Step-by-step explanation:
Hello, great question. These types are questions are the beginning steps for learning more advanced Algebraic Equations.
We first need to create of formula to then be able to solve this by plugging any amount of sales. The formula needs to <u><em>multiply</em></u> 10% in decimal form which is the commission rate (got from the comments) by the total price of the amount sold. Then <u><em>subtract</em></u> $10 from that amount.

Now that we have the formula we can plug in the amount in sales to calculate how much he has left after eating lunch.



We can see that if Marcus sells $3,500 worth of product then after eating lunch he would have $340 left.
I hope this answered your question. If you have any more questions feel free to ask away at Brainly.