Opal was saving money to buy pens. She saved $8 every 3 days. After saving for 24 days, she went to buy pens that were on sale.
- What was the most number of pens she could buy?
- Opal wanted to buy 59 pens. How much more did she need to save?
(a)
Number of sets of 3 days
= 24 ÷ 3
= 8
Amount that Opal saved in 24 days
= 8 x 8
= $64
Maximum number of sets of 9 pens that Opal could buy
= 64 ÷ 13
= 4 r $12
Remaining amount left after buying sets of 9 pens = $12
Maximum number of sets of 5 pens that Opal could buy with $12
= 12 ÷ 8
= 1 r $4
Remaining amount left after buying sets of 5 pens = $4
Maximum number of pens that Opal could buy with $4
= 4 ÷ 4
= 1
Most number of pens that Opal could buy
= 4 x 9 + 1 x 5 + 1
= 36 + 5 + 1
= 42
(b)
Number of sets of 9 pens that Opal could buy
= 59 ÷ 9
= 6 r 5
Number of sets of 5 pens that Opal could buy
= 5 ÷ 5
= 1 r 0
Amount that Opal needed to buy 59 pens
= 6 x 13 + 1 x 8
= 78 + 8
= $86
Amount that Opal needed to save more
= 86 - 64
= $22
Answer(s): (a) 42; (b) $22
