Some stickers are packed into exactly packets of 20.
If the stickers are repacked into packets of 7,
there are 5 more packets and 4 stickers left.
- How many packets are there?
- How many stickers are there?
|
Packets of 20 |
Packets of 7 |
Number |
1 u |
1 u + 5 |
Value |
20 |
7 |
Total value |
20 u |
7(1 u + 5) + 4 = 7 u + 39 |
(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 7
= 7 x (1 u + 5) + 4
= 7 u + 35 + 4
= 7 u + 39
20 u = 7 u + 39
20 u - 7 u = 39
13 u = 39
1 u = 39 ÷ 13 = 3
Number of packets of 20
= 1 u
= 3
(b)
Number of stickers
= 20 u
= 20 x 3
= 60
Answer(s): (a) 3; (b) 60