Emily was saving money to buy pens. She saved $9 every 7 days. After saving for 42 days, she went to buy pens that were on sale.
- What was the most number of pens she could buy?
- Emily wanted to buy 39 pens. How much more did she need to save?
(a)
Number of sets of 7 days
= 42 ÷ 7
= 6
Amount that Emily saved in 42 days
= 6 x 9
= $54
Maximum number of sets of 7 pens that Emily could buy
= 54 ÷ 11
= 4 r $10
Remaining amount left after buying sets of 7 pens = $10
Maximum number of sets of 3 pens that Emily could buy with $10
= 10 ÷ 6
= 1 r $4
Remaining amount left after buying sets of 3 pens = $4
Maximum number of pens that Emily could buy with $4
= 4 ÷ 4
= 1
Most number of pens that Emily could buy
= 4 x 7 + 1 x 3 + 1
= 28 + 3 + 1
= 32
(b)
Number of sets of 7 pens that Emily could buy
= 39 ÷ 7
= 5 r 4
Number of sets of 3 pens that Emily could buy
= 4 ÷ 3
= 1 r 1
Number of individual pens that Emily could buy = 1
Amount that Emily needed to buy 39 pens
= 5 x 11 + 1 x 6 + 4
= 55 + 6 + 4
= $65
Amount that Emily needed to save more
= 65 - 54
= $11
Answer(s): (a) 32; (b) $11
