Some stickers are packed into exactly packets of 9.
If the stickers are repacked into packets of 20,
there are 5 less packets and needs 8 more stickers to make another packet.
- How many packets are there?
- How many stickers are there?
|
Packets of 9 |
Packets of 20 |
Number |
1 u |
1 u - 5 |
Value |
9 |
20 |
Total value |
9 u |
20 u - 88 |
(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
= 20 - 8
= 12
Number of stickers if they are in packets of 20
= 20(1 u - 5) + 12
= 20 u - 100 + 12
= 20 u - 88
9 u = 20 u - 88
20 u - 9 u = 88
11 u = 88
1 u = 88 ÷ 11 = 8
Number of packets of 9
= 1 u
= 8
(b)
Number of stickers
= 9 u
= 9 x 8
= 72
Answer(s): (a) 8; (b) 72