Nora, Yoko, Nicole and Emily jointly contributed to the cost of a present for their brother. Nora's contribution is ¹₈ of the total contribution made by the four girls. The ratio of Emily's contribution to the total of Yoko's and Nicole's contribution is 5 : 2. What is the total contribution by the four girls if Yoko's contribution is ²₃ of Nicole's contribution and the total amount contributed by Nora and Emily is $300?

Nora	Yoko	Nicole	Emily	Total
1x5	7x5			8x5
	2x5		5x5
	2x2	3x2
5 u	4 u	6 u	25 u	40 u

Working backwards.

Total amount that Yoko and Nicole had is the combined repeated identity.
LCM of 2 and 5 = 10

Total amount that Yoko, Nicole and Emily had is the next combined repeated identity.
LCM of 7 and 5 = 35 

Total amount contributed by Nora and Emily
= 5 u + 25 u
= 30 u

30 u = 300

2 u = 300 ÷ 30 = $10

Total contribution by the four girls
= 40 u
= 40 x 10
= $400

Answer(s): $400