Yoko and Lynn had a total of 168 marbles. Lynn gave ¹₄ of her marbles to Yoko. In return, Yoko gave ¹₈ of the total number of marbles that she had to Lynn. In the end, each girl had the same number of marbles. How many marbles did Yoko have at first?

	Yoko	Lynn	Total
Before 1	?	4 u	168
Change 1	+ 1 u	- 1 u
After 1	96	3 u	168
Before 2	8 p	3 u	168
Change 2	- 1 p	+ 1 p
After 2	7 p (84)	84	168

Since Lynn gave some marbles to Yoko and Yoko then gave some marbles to Lynn, it is an internal transfer of marbles between the two girls. So, the total number of marbles remains unchanged.

Number of marbles that Lynn and Yoko each had in the end is the same.

Number of marbles that Yoko had in the end
= 168 ÷ 2
= 84

Number of marbles that Yoko had in the end = 7 p

7 p = 84

1 p = 84 ÷ 7 = 12

Number of marbles that Yoko had after receiving some marbles from Lynn
= 8 p
= 8 x 12
= 96

Number of marbles that Lynn had after giving to Yoko
= 168 - 96
= 72

3 u = 72

1 u = 72 ÷ 3 = 24

Number of marbles that Lynn had at first
= 4 u
= 4 x 24
= 96

Number of marbles that Yoko had at first
= 168 - 96
= 72

Answer(s): 72