Some stickers are packed into exactly packets of 15.
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 15 |
Packets of 9 |
Number |
1 u |
1 u + 4 |
Value |
15 |
9 |
Total value |
15 u |
9 u + 36 |
(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 + 4)
= 9 u + 36
9 u + 36 = 15 u
15 u - 9 u = 36
6 u = 36
1 u = 36 ÷ 6 = 6
Number of packets of 9
= 1 u + 4
= 6 + 4
= 10
(b)
Number of stickers
= 15 u
= 15 x 6
= 90
Answer(s): (a) 10; (b) 90