Some stickers are packed into exactly packets of 18.
If the stickers are repacked into packets of 9,
there are 4 more packets.
- How many packets of 9 are there?
- How many stickers are there?
|
Packets of 18 |
Packets of 9 |
Number |
1 u |
1 u + 4 |
Value |
18 |
9 |
Total value |
18 u |
9 u + 36 |
(a)
Let the number of packets of 18 be 1 u.
Number of stickers if they are in packets of 18
= 18 x 1 u
= 18 u
Number of stickers if they are in packets of 9
= 9 x (1 u + 4)
= 9 u + 36
9 u + 36 = 18 u
18 u - 9 u = 36
9 u = 36
1 u = 36 ÷ 9 = 4
Number of packets of 9
= 1 u + 4
= 4 + 4
= 8
(b)
Number of stickers
= 18 u
= 18 x 4
= 72
Answer(s): (a) 8; (b) 72