Some stickers are packed into exactly packets of 15.
If the stickers are repacked into packets of 9,
there are 8 more packets.
- How many packets of 9 are there?
- How many stickers are there?
|
Packets of 15 |
Packets of 9 |
Number |
1 u |
1 u + 8 |
Value |
15 |
9 |
Total value |
15 u |
9 u + 72 |
(a)
Let the number of packets of 15 be 1 u.
Number of stickers if they are in packets of 15
= 15 x 1 u
= 15 u
Number of stickers if they are in packets of 9
= 9 x (1 u + 8)
= 9 u + 72
9 u + 72 = 15 u
15 u - 9 u = 72
6 u = 72
1 u = 72 ÷ 6 = 12
Number of packets of 9
= 1 u + 8
= 12 + 8
= 20
(b)
Number of stickers
= 15 u
= 15 x 12
= 180
Answer(s): (a) 20; (b) 180