Jean, Tina, Victoria and Dana jointly contributed to the cost of a present for their sister. Jean's contribution is ⁷₈ of the total contribution made by the four girls. The ratio of Dana's contribution to the total of Tina's and Victoria's contribution is 2 : 1. What is the total contribution by the four girls if Tina's contribution is ¹₄ of Victoria's contribution and the total amount contributed by Jean and Dana is $1840?

Jean	Tina	Victoria	Dana	Total
7x15	1x15			8x15
	1x5		2x5
	1x1	4x1
105 u	1 u	4 u	10 u	120 u

Working backwards.

Total amount that Tina and Victoria had is the combined repeated identity.
LCM of 1 and 5 = 5

Total amount that Tina, Victoria and Dana had is the next combined repeated identity.
LCM of 1 and 15 = 15 

Total amount contributed by Jean and Dana
= 105 u + 10 u
= 115 u

115 u = 1840

1 u = 1840 ÷ 115 = $16

Total contribution by the four girls
= 120 u
= 120 x 16
= $1920

Answer(s): $1920