Yen, Roshel, Jen and Victoria jointly contributed to the cost of a present for their brother. Yen's contribution is ⁷₁₀ of the total contribution made by the four girls. The ratio of Victoria's contribution to the total of Roshel's and Jen's contribution is 5 : 1. What is the total contribution by the four girls if Roshel's contribution is ²₇ of Jen's contribution and the total amount contributed by Yen and Victoria is $855?

Yen	Roshel	Jen	Victoria	Total
7x18	3x18			10x18
	1x9		5x9
	2x1	7x1
126 u	2 u	7 u	45 u	180 u

Working backwards.

Total amount that Roshel and Jen had is the combined repeated identity.
LCM of 1 and 9 = 9

Total amount that Roshel, Jen and Victoria had is the next combined repeated identity.
LCM of 3 and 18 = 54 

Total amount contributed by Yen and Victoria
= 126 u + 45 u
= 171 u

171 u = 855

1 u = 855 ÷ 171 = $5

Total contribution by the four girls
= 180 u
= 180 x 5
= $900

Answer(s): $900