Elyse was saving money to buy pens. She saved $8 every 7 days. After saving for 28 days, she went to buy pens that were on sale.

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

(a)
Number of sets of 7 days
= 28 ÷ 7
= 4

Amount that Elyse saved in 28 days
= 4 x 8
= $32

Maximum number of sets of 6 pens that Elyse could buy 
= 32 ÷ 11
= 2 r $10

Remaining amount left after buying sets of 6 pens = $10

Maximum number of sets of 3 pens that Elyse could buy with $10
= 10 ÷ 6
= 1 r $4 

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

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

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

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

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

Number of individual pens that Elyse could buy = 1

Amount that Elyse needed to buy 22 pens
= 3 x 11 + 1 x 6 + 4
= 33 + 6 + 4
= $43

Amount that Elyse needed to save more
= 43 - 32
= $11

Answer(s): (a) 16; (b) $11