Ivory and Tammy had a total of 144 erasers. Tammy gave ¹₄ of her erasers to Ivory. In return, Ivory gave ¹₇ of the total number of erasers that she had to Tammy. In the end, each girl had the same number of erasers. How many erasers did Ivory have at first?

	Ivory	Tammy	Total
Before 1	?	4 u	144
Change 1	+ 1 u	- 1 u
After 1	84	3 u	144
Before 2	7 p	3 u	144
Change 2	- 1 p	+ 1 p
After 2	6 p (72)	72	144

Since Tammy gave some erasers to Ivory and Ivory then gave some erasers to Tammy, it is an internal transfer of erasers between the two girls. So, the total number of erasers remains unchanged.

Number of erasers that Tammy and Ivory each had in the end is the same.

Number of erasers that Ivory had in the end
= 144 ÷ 2
= 72

Number of erasers that Ivory had in the end = 6 p

6 p = 72

1 p = 72 ÷ 6 = 12

Number of erasers that Ivory had after receiving some erasers from Tammy
= 7 p
= 7 x 12
= 84

Number of erasers that Tammy had after giving to Ivory
= 144 - 84
= 60

3 u = 60

1 u = 60 ÷ 3 = 20

Number of erasers that Tammy had at first
= 4 u
= 4 x 20
= 80

Number of erasers that Ivory had at first
= 144 - 80
= 64

Answer(s): 64