A bookshop sells markers in packs of 2 and 5. At first, there were 4 times as many packs of 2 as packs of 5. After selling half of the packs of 2 and some packs of 5, Mr Heng packs 19 additional packs of 5. How many packs of 2 and 5 are sold if there are 8 times as many packs of 2 as packs of 5 and there is a total of 126 unsold markers?

	Packs of 2	Packs of 5
Comparing the number of packs at first	4x4 = 16 u	1x4 = 4 u
Before	2x8 = 16 u
Change 1	- 1x8 = - 8 u	- ?
Change 2		+ 19
After	1x8 = 8 u
Comparing the number of packs in the end	8 u	1 u

The number of packs of 2 in the end is repeated. Make the number of packs of 2 in the end the same. LCM of 1 and 8 is 8.

The number of packs of 2 at first is repeated. Make the number of packs of 2 at first the same. LCM of 16 and 4 is 16.

Number of markers left unsold	Packs of 2	Packs of 5	Total
Number	8 u	1 u
Value	2	5
Total value	16 u	5 u	21 u

Total number of markers left unsold
= (8 u x 2) + (1 u x 5)
= 16 u + 5 u
= 21 u

21 u = 126

1 u = 126 ÷ 21 = 6

Number of packs of 2 and 5  sold
= 8 u + (4 u - 1 u) + 19
= 8 u + 3 u + 19
= 11 u + 19
= 11 x 6 + 19
= 66 + 19
= 85

Answer(s): 85