Answer:
The grid is formed by 100 small squares, therefore the correct option must have 75 painted squares and it's option "a".
Explanation:
In order to choose the correct grid we first need to calculate the percentage of friends that brought their lunch from home. To do that we need to divide the number of friends that brought their lunch by the total of friends sitting at the table and multiply it by 100. We have:
brought lunch (%) = (brought lunch / number of friends)*100
brought lunch (%) = (6/8)*100
brought lunch (%) = 75 %
The grid is formed by 100 small squares, therefore the correct option must have 75 painted squares and it's option "a".