Some stickers are packed into exactly packets of 13.
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 13 |
Packets of 9 |
Number |
1 u |
1 u + 4 |
Value |
13 |
9 |
Total value |
13 u |
9 u + 36 |
(a)
Let the number of packets of 13 be 1 u.
Number of stickers if they are in packets of 13
= 13 x 1 u
= 13 u
Number of stickers if they are in packets of 9
= 9 x (1 u + 4)
= 9 u + 36
9 u + 36 = 13 u
13 u - 9 u = 36
4 u = 36
1 u = 36 ÷ 4 = 9
Number of packets of 9
= 1 u + 4
= 9 + 4
= 13
(b)
Number of stickers
= 13 u
= 13 x 9
= 117
Answer(s): (a) 13; (b) 117