Zoe was saving money to buy pens. She saved $6 every 4 days. After saving for 36 days, she went to buy pens that were on sale.
- What was the most number of pens she could buy?
- Zoe wanted to buy 28 pens. How much more did she need to save?
(a)
Number of sets of 4 days
= 36 ÷ 4
= 9
Amount that Zoe saved in 36 days
= 9 x 6
= $54
Maximum number of sets of 5 pens that Zoe could buy
= 54 ÷ 11
= 4 r $10
Remaining amount left after buying sets of 5 pens = $10
Maximum number of sets of 3 pens that Zoe could buy with $10
= 10 ÷ 7
= 1 r $3
Remaining amount left after buying sets of 3 pens = $3
Maximum number of pens that Zoe could buy with $3
= 3 ÷ 3
= 1
Most number of pens that Zoe could buy
= 4 x 5 + 1 x 3 + 1
= 20 + 3 + 1
= 24
(b)
Number of sets of 5 pens that Zoe could buy
= 28 ÷ 5
= 5 r 3
Number of sets of 3 pens that Zoe could buy
= 3 ÷ 3
= 1 r 0
Amount that Zoe needed to buy 28 pens
= 5 x 11 + 1 x 7
= 55 + 7
= $62
Amount that Zoe needed to save more
= 62 - 54
= $8
Answer(s): (a) 24; (b) $8
