Cindy was saving money to buy pens. She saved $4 every 7 days. After saving for 112 days, she went to buy pens that were on sale.
- What was the most number of pens she could buy?
- Cindy wanted to buy 39 pens. How much more did she need to save?
(a)
Number of sets of 7 days
= 112 ÷ 7
= 16
Amount that Cindy saved in 112 days
= 16 x 4
= $64
Maximum number of sets of 6 pens that Cindy could buy
= 64 ÷ 13
= 4 r $12
Remaining amount left after buying sets of 6 pens = $12
Maximum number of sets of 3 pens that Cindy could buy with $12
= 12 ÷ 8
= 1 r $4
Remaining amount left after buying sets of 3 pens = $4
Maximum number of pens that Cindy could buy with $4
= 4 ÷ 4
= 1
Most number of pens that Cindy could buy
= 4 x 6 + 1 x 3 + 1
= 24 + 3 + 1
= 28
(b)
Number of sets of 6 pens that Cindy could buy
= 39 ÷ 6
= 6 r 3
Number of sets of 3 pens that Cindy could buy
= 3 ÷ 3
= 1 r 0
Amount that Cindy needed to buy 39 pens
= 6 x 13 + 1 x 8
= 78 + 8
= $86
Amount that Cindy needed to save more
= 86 - 64
= $22
Answer(s): (a) 28; (b) $22
