Some stickers are packed into exactly packets of 7.
If the stickers are repacked into packets of 15,
there are 5 less packets and 3 stickers extra.
- How many packets are there?
- How many stickers are there?
|
Packets of 7 |
Packets of 15 |
Number |
1 u |
1 u - 5 |
Value |
7 |
15 |
Total value |
7 u |
15 u - 72 |
(a)
Let the number of packets of 7 be 1 u.
Number of stickers if they are in packets of 7
= 1 u x 7
= 7 u
Number of stickers if they are in packets of 15
= 15(1 u - 5) + 3
= 15 u - 75 + 3
= 15 u - 72
7 u = 15 u - 72
15 u - 7 u = 72
8 u = 72
1 u = 72 ÷ 8 = 9
Number of packets of 7
= 1 u
= 9
(b)
Number of stickers
= 7 u
= 7 x 9
= 63
Answer(s): (a) 9; (b) 63