Some stickers are packed into exactly packets of 9.
If the stickers are repacked into packets of 15,
there are 2 less packets and needs 3 more stickers to make another packet.
- How many packets are there?
- How many stickers are there?
|
Packets of 9 |
Packets of 15 |
Number |
1 u |
1 u - 2 |
Value |
9 |
15 |
Total value |
9 u |
15 u - 18 |
(a)
Let the number of packets of 9 be 1 u.
Number of stickers if they are in packets of 9
= 1 u x 9
= 9 u
Number of stickers left if another packet is not packed
= 15 - 3
= 12
Number of stickers if they are in packets of 15
= 15(1 u - 2) + 12
= 15 u - 30 + 12
= 15 u - 18
9 u = 15 u - 18
15 u - 9 u = 18
6 u = 18
1 u = 18 ÷ 6 = 3
Number of packets of 9
= 1 u
= 3
(b)
Number of stickers
= 9 u
= 9 x 3
= 27
Answer(s): (a) 3; (b) 27