Roshel, Zoe, Ivory and Vanessa jointly contributed to the cost of a present for their schoolmate. Roshel's contribution is ⁴₅ of the total contribution made by the four girls. The ratio of Vanessa's contribution to the total of Zoe's and Ivory's contribution is 2 : 1. What is the total contribution by the four girls if Zoe's contribution is ¹₃ of Ivory's contribution and the total amount contributed by Roshel and Vanessa is $672?

Roshel	Zoe	Ivory	Vanessa	Total
4x12	1x12			5x12
	1x4		2x4
	1x1	3x1
48 u	1 u	3 u	8 u	60 u

Working backwards.

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

Total amount that Zoe, Ivory and Vanessa had is the next combined repeated identity.
LCM of 1 and 12 = 12 

Total amount contributed by Roshel and Vanessa
= 48 u + 8 u
= 56 u

56 u = 672

1 u = 672 ÷ 56 = $12

Total contribution by the four girls
= 60 u
= 60 x 12
= $720

Answer(s): $720