Marion was saving money to buy pens. She saved $5 every 8 days. After saving for 56 days, she went to buy pens that were on sale.

1. What was the most number of pens she could buy?
2. Marion wanted to buy 22 pens. How much more did she need to save?

(a)
Number of sets of 8 days
= 56 ÷ 8
= 7

Amount that Marion saved in 56 days
= 7 x 5
= $35

Maximum number of sets of 6 pens that Marion could buy 
= 35 ÷ 12
= 2 r $11

Remaining amount left after buying sets of 6 pens = $11

Maximum number of sets of 3 pens that Marion could buy with $11
= 11 ÷ 7
= 1 r $4 

Remaining amount left after buying sets of 3 pens = $4

Maximum number of pens that Marion could buy with $4 
= 4 ÷ 4
= 1

Most number of pens that Marion could buy
= 2 x 6 + 1 x 3 + 1
= 12 + 3 + 1
= 16

(b)
Number of sets of 6 pens that Marion could buy
= 22 ÷ 6
= 3 r 4

Number of sets of 3 pens that Marion could buy
= 4 ÷ 3
= 1 r 1

Number of individual pens that Marion could buy = 1

Amount that Marion needed to buy 22 pens
= 3 x 12 + 1 x 7 + 4
= 36 + 7 + 4
= $47

Amount that Marion needed to save more
= 47 - 35
= $12

Answer(s): (a) 16; (b) $12