Answer:
215 hamburgers
Explanation:
First, you need to find out what 570 divided by 2 is. It's 285 (570/2=285)
Next, you need to add 70 to 285. It's 355 (285+70=355)
Lastly, you need to subtract 355 from 570. It's 215 (570-355=215)
Thus, the were 215 hamburgers sold on Monday.
Hope this is right and helps!