Answer:
(20-6) ÷ 7 = 2
Explanation:
It says she lost 6 of 20 marbles, lost being a key word for subtraction. You have to put parentheses [ ( ) ] because she lost the marbles before giving them to her friends. She has 7 friends, so divide by 7. The answer to the problem would be 2.
I hope this helps! :)