Diana, Abi, Pamela and Eva jointly contributed to the cost of a present for their classmate. Diana's contribution is ⁷₁₀ of the total contribution made by the four girls. The ratio of Eva's contribution to the total of Abi's and Pamela's contribution is 2 : 1. What is the total contribution by the four girls if Abi's contribution is ¹₃ of Pamela's contribution and the total amount contributed by Diana and Eva is $504?

Diana	Abi	Pamela	Eva	Total
7x4	3x4			10x4
	1x4		2x4
	1x1	3x1
28 u	1 u	3 u	8 u	40 u

Working backwards.

Total amount that Abi and Pamela had is the combined repeated identity.
LCM of 1 and 4 = 4

Total amount that Abi, Pamela and Eva had is the next combined repeated identity.
LCM of 3 and 4 = 12 

Total amount contributed by Diana and Eva
= 28 u + 8 u
= 36 u

36 u = 504

1 u = 504 ÷ 36 = $14

Total contribution by the four girls
= 40 u
= 40 x 14
= $560

Answer(s): $560