Kathy was saving money to buy pens. She saved $7 every 4 days. After saving for 20 days, she went to buy pens that were on sale.
- What was the most number of pens she could buy?
- Kathy wanted to buy 45 pens. How much more did she need to save?
(a)
Number of sets of 4 days
= 20 ÷ 4
= 5
Amount that Kathy saved in 20 days
= 5 x 7
= $35
Maximum number of sets of 8 pens that Kathy could buy
= 35 ÷ 9
= 3 r $8
Remaining amount left after buying sets of 8 pens = $8
Maximum number of sets of 5 pens that Kathy could buy with $8
= 8 ÷ 6
= 1 r $2
Remaining amount left after buying sets of 5 pens = $2
Maximum number of pens that Kathy could buy with $2
= 2 ÷ 2
= 1
Most number of pens that Kathy could buy
= 3 x 8 + 1 x 5 + 1
= 24 + 5 + 1
= 30
(b)
Number of sets of 8 pens that Kathy could buy
= 45 ÷ 8
= 5 r 5
Number of sets of 5 pens that Kathy could buy
= 5 ÷ 5
= 1 r 0
Amount that Kathy needed to buy 45 pens
= 5 x 9 + 1 x 6
= 45 + 6
= $51
Amount that Kathy needed to save more
= 51 - 35
= $16
Answer(s): (a) 30; (b) $16
