Roshel, Jade, Sarah and Nora jointly contributed to the cost of a present for their brother. Roshel's contribution is ¹₂ of the total contribution made by the four girls. The ratio of Nora's contribution to the total of Jade's and Sarah's contribution is 5 : 2. What is the total contribution by the four girls if Jade's contribution is ¹₇ of Sarah's contribution and the total amount contributed by Roshel and Nora is $624?

Roshel	Jade	Sarah	Nora	Total
1x28	1x28			2x28
	2x4		5x4
	1x1	7x1
28 u	1 u	7 u	20 u	56 u

Working backwards.

Total amount that Jade and Sarah had is the combined repeated identity.
LCM of 2 and 8 = 8

Total amount that Jade, Sarah and Nora had is the next combined repeated identity.
LCM of 1 and 28 = 28 

Total amount contributed by Roshel and Nora
= 28 u + 20 u
= 48 u

48 u = 624

2 u = 624 ÷ 48 = $13

Total contribution by the four girls
= 56 u
= 56 x 13
= $728

Answer(s): $728