Answer:
n+(n+6)=24
Explanation:
we know that he has 24 in total so it has to equal 24
we also know that he has 6 more marbles meaning he has n number of yellow marbles plus 6 and that will give you the total of the blue marbles he also has n number of yellow marbles that he has to add to the number of blue marbles to get the total of 24