Mrs Goh gave Penelope and Shannon some money each on Wednesday. On Thursday, Penelope gave ¹₆ of the amount she had to Shannon. On Friday, Shannon gave ¹₅ of the amount she had to Penelope. In the end, Penelope had $18 and Shannon had $12. How much did Shannon had more than Penelope at first?

	Penelope	Shannon	Total
Before 1	6 u	?	$30
Change 1	- 1 u	+ 1 u
After 1	5 u	5 p	$30
Before 2	$18 - 1 p	5 p	$30
Change 2	+ 1 p	- 1 p
After 2	$18	4 p ($12)	$30

Amount that Shannon had in the end = 4 p

4 p = 12

1 p = 12 ÷ 4 = 3

Working backwards.

Amount that Penelope had after giving to Shannon on Thursday
= 18 - 1 p
= 18 - 3
= $15

5 u = 15

1 u = 15 ÷ 5 = 3

Amount that Penelope had at first
= 6 u
= 6 x 3
= $18

Total amount that Penelope and Shannon had 
= 18 + 12
= $30

Amount that Shannon had at first
= 30 - 18
= $12

Amount that Penelope had more than Shannon
= 18 - 12 
= $6

Answer(s): $6