Some stickers are packed into exactly packets of 9.
If the stickers are repacked into packets of 15,
there are 8 less packets.
- How many packets are there?
- How many stickers are there?
|
Packets of 9 |
Packets of 15 |
Number |
1 u |
1 u - 8 |
Value |
9 |
15 |
Total value |
9 u |
15(1 u - 8) = 15 u - 120 |
(a)
Let the number of packets of 9 be 1 u.
Number of stickers in packets of 9
= 1 u x 9
= 9 u
Number of stickers in packets of 15
= 15 x (1 u - 8)
= 15 u - 120
9 u = 15 u - 120
15 u - 9 u = 120
6 u = 120
1 u = 120 ÷ 6 = 20
Number of packets of 9 = 20
(b)
Number of stickers
= 9 u
= 9 x 20
= 180
Answer(s): (a) 20; (b) 180