Answer:
Rachel and Sean each had 56 marbles at first.
Explanation:
Let x be the number of marbles Rachel and Sean had at first.
Rachel had x - 20 marbles after giving away 20 marbles.
Sean had x - 44 marbles after giving away 44 marbles.
So,

Opening bracket on the right side:

Adding both side by 132.


Subtracting x on both sides.


Dividing both sides by 2:


So,

Therefore, Rachel and Sean each had 56 marbles at first.