Dana was saving money to buy pens. She saved $3 every 5 days. After saving for 65 days, she went to buy pens that were on sale.
- What was the most number of pens she could buy?
- Dana wanted to buy 38 pens. How much more did she need to save?
(a)
Number of sets of 5 days
= 65 ÷ 5
= 13
Amount that Dana saved in 65 days
= 13 x 3
= $39
Maximum number of sets of 7 pens that Dana could buy
= 39 ÷ 8
= 4 r $7
Remaining amount left after buying sets of 7 pens = $7
Maximum number of sets of 3 pens that Dana could buy with $7
= 7 ÷ 5
= 1 r $2
Remaining amount left after buying sets of 3 pens = $2
Maximum number of pens that Dana could buy with $2
= 2 ÷ 2
= 1
Most number of pens that Dana could buy
= 4 x 7 + 1 x 3 + 1
= 28 + 3 + 1
= 32
(b)
Number of sets of 7 pens that Dana could buy
= 38 ÷ 7
= 5 r 3
Number of sets of 3 pens that Dana could buy
= 3 ÷ 3
= 1 r 0
Amount that Dana needed to buy 38 pens
= 5 x 8 + 1 x 5
= 40 + 5
= $45
Amount that Dana needed to save more
= 45 - 39
= $6
Answer(s): (a) 32; (b) $6