Answer: The 6 burgers cost $40.20 and each burger costs $6.70.
Explanation:
If she gave $50 to the waitress and received back $9.80 as a change, then subtract $9.80 from $50 to find the original price of the 6 burgers.
50 - 9.80 = 40.20 This means the 6 burgers cost $40.20 and to find how the price of each burger, divide 40.20 by 6.
40.20/6 = 6.70