A stationery booth sells markers in packs of 3 and 4. At first, there were 4 times as many packs of 3 as packs of 4. After selling half of the packs of 3 and some packs of 4, Mr Thia packs 14 additional packs of 4. How many packs of 3 are sold if there are 6 times as many packs of 3 as packs of 4 and there is a total of 66 unsold markers?
| |
Packs of 3 |
Packs of 4 |
Comparing the number
of packs at first |
4x3 =
12 u |
1x3 =
3 u |
| Before |
2x6 =
12 u |
|
| Change 1 |
- 1x6 =
- 6 u |
- ? |
| Change 2 |
|
+ 14 |
| After |
1x6 =
6 u |
|
Comparing the number
of packs in the end |
6 u |
1 u |
The number of packs of 3 in the end is repeated. Make the number of packs of 3 in the end the same. LCM of 1 and 6 is 6.
The number of packs of 3 at first is repeated. Make the number of packs of 3 at first the same. LCM of 12 and 4 is 12.
Number of markers
left unsold |
Packs of 3
|
Packs of 4
|
Total
|
| Number |
6 u |
1 u |
|
| Value |
3 |
4 |
|
| Total value |
18 u |
4 u |
22 u |
Total number of markers left unsold
= (6 u x 3) + (1 u x 4)
= 18 u + 4 u
= 22 u
22 u = 66
1 u = 66 ÷ 22 = 3
Number of packs of 4 sold
= (3 u - 1 u) + 14
= 2 u + 14
= 2 x 3 + 14
= 6 + 14
= 20
Answer(s): 20
