Sabrina, Esther, Gwen and Erika went to buy a souvenir for their grandmother. They shared the cost equally among themselves. However, Erika forgot to bring her money. So, the other 3 girls paid for the souvenir first. Gwen paid ⁷₉ of the amount Sabrina and Esther paid. Esther paid $4 more than Sabrina. The next day, Erika returned $30 to Gwen and some money to Sabrina and Esther. How much did Erika return to

1. Sabrina?
2. Esther?

	Sabrina	Esther	Gwen	Erika	Total
Comparing the amounts 3 girls paid first	9 u		7 u		16 u
Comparing the amounts 2 girls paid first	1 p	1 p + 4
Amounts that each girl paid for Erika first	- ?	- ?	- 30	+ 30 + ?
Comparing the amounts each girl should pay	1x4 = 4 u	1x4 = 4 u	1x4 = 4 u	1x4 = 4 u	4x4 = 16 u

(a)
The total amount that the 4 girls paid is repeated. Make the total amount the same.  LCM of 4 and 16 is 16.

Extra amount that Gwen paid 
= 7 u - 4 u
= 3 u

3 u = 30

1 u = 30 ÷ 3 = 10

Total amount that Sabrina and Esther paid at first
= 9 u
= 9 x 10
= $90

1 p + 1 p + 4 = 90
2 p = 90 - 4
2 p = 86

1 p = 86 ÷ 2 = 43

Amount that Erika needed to pay Sabrina
= 1 p - 4 u
= 43 - 4 x 10
= 43 - 40
= $3

(b)
Amount that Erika needed to pay Esther
= (1 p + 4) - 4 u
= (43 + 4) - 4 x 10
= 47 - 40
= $7

Answer(s): (a) $3; (b) $7