Jaslyn, Shiyun, Eva and Zara jointly contributed to the cost of a present for their colleague. Jaslyn's contribution is ⁴₉ of the total contribution made by the four girls. The ratio of Zara's contribution to the total of Shiyun's and Eva's contribution is 3 : 2. What is the total contribution by the four girls if Shiyun's contribution is ¹₈ of Eva's contribution and the total amount contributed by Jaslyn and Zara is $315?

Jaslyn	Shiyun	Eva	Zara	Total
4x9	5x9			9x9
	2x9		3x9
	1x2	8x2
36 u	2 u	16 u	27 u	81 u

Working backwards.

Total amount that Shiyun and Eva had is the combined repeated identity.
LCM of 2 and 9 = 18

Total amount that Shiyun, Eva and Zara had is the next combined repeated identity.
LCM of 5 and 9 = 45 

Total amount contributed by Jaslyn and Zara
= 36 u + 27 u
= 63 u

63 u = 315

2 u = 315 ÷ 63 = $5

Total contribution by the four girls
= 81 u
= 81 x 5
= $405

Answer(s): $405