Some stickers are packed into exactly packets of 10.
If the stickers are repacked into packets of 9,
there are 7 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 + 7 |
Value |
10 |
9 |
Total value |
10 u |
9 u + 63 |
(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 + 7)
= 9 u + 63
9 u + 63 = 10 u
10 u - 9 u = 63
1 u = 63
1 u = 63 ÷ 1 = 63
Number of packets of 9
= 1 u + 7
= 63 + 7
= 70
(b)
Number of stickers
= 10 u
= 10 x 63
= 630
Answer(s): (a) 70; (b) 630