Some stickers are packed into exactly packets of 10.
If the stickers are repacked into packets of 9,
there are 2 more packets.
- How many packets of 9 are there?
- How many stickers are there?
|
Packets of 10 |
Packets of 9 |
Number |
1 u |
1 u + 2 |
Value |
10 |
9 |
Total value |
10 u |
9 u + 18 |
(a)
Let the number of packets of 10 be 1 u.
Number of stickers if they are in packets of 10
= 10 x 1 u
= 10 u
Number of stickers if they are in packets of 9
= 9 x (1 u + 2)
= 9 u + 18
9 u + 18 = 10 u
10 u - 9 u = 18
1 u = 18
1 u = 18 ÷ 1 = 18
Number of packets of 9
= 1 u + 2
= 18 + 2
= 20
(b)
Number of stickers
= 10 u
= 10 x 18
= 180
Answer(s): (a) 20; (b) 180