Some stickers are packed into exactly packets of 20.
If the stickers are repacked into packets of 9,
there are 8 more packets and 5 stickers left.
- How many packets are there?
- How many stickers are there?
|
Packets of 20 |
Packets of 9 |
Number |
1 u |
1 u + 8 |
Value |
20 |
9 |
Total value |
20 u |
9(1 u + 8) + 5 = 9 u + 77 |
(a)
Let the number of packets of 20 be 1 u.
Number of stickers if they are in packets of 20
= 1 u x 20
= 20 u
Number of stickers if they are in packets of 9
= 9 x (1 u + 8) + 5
= 9 u + 72 + 5
= 9 u + 77
20 u = 9 u + 77
20 u - 9 u = 77
11 u = 77
1 u = 77 ÷ 11 = 7
Number of packets of 20
= 1 u
= 7
(b)
Number of stickers
= 20 u
= 20 x 7
= 140
Answer(s): (a) 7; (b) 140