Neave and Sean had 64 marbles in total. Sean had 10 marbles more than Neave at first. After Neave and Sean played a game with Natalie, Neave had ¹₃ as many marbles as Sean. If Neave lost as many marbles as Sean to Natalie, find the number of marbles that Neave lost to Natalie.

	Neave	Sean	Difference
Before	1 u	1 u + 10	10
Change	- ?	- ?
After	1 p	3 p	2 p

Total number of marbles at first
= 1 u + 1 u + 10 
= 2 u + 10

2 u + 10 = 64
2 u = 64 - 10
2 u = 54

1 u = 54 ÷ 2 = 27

Since Neave lost the same number of marbles as Sean, the difference in the number of marbles between Neave and Sean at first and in the end remains the same.

Difference in the number of marbles in the end
= 3 p - 1 p
= 2 p

2 p = 10

1 p = 10 ÷ 2 = 5

Number of marbles that Neave lost to Natalie
= 1 u - 1 p
= 27 - 1 x 5
= 27 - 5
= 22

Answer(s): 22