Esther, Eva, Zoe and Barbara jointly contributed to the cost of a present for their colleague. Esther's contribution is ⁷₈ of the total contribution made by the four girls. The ratio of Barbara's contribution to the total of Eva's and Zoe's contribution is 2 : 1. What is the total contribution by the four girls if Eva's contribution is ¹₆ of Zoe's contribution and the total amount contributed by Esther and Barbara is $1449?

Esther	Eva	Zoe	Barbara	Total
7x21	1x21			8x21
	1x7		2x7
	1x1	6x1
147 u	1 u	6 u	14 u	168 u

Working backwards.

Total amount that Eva and Zoe had is the combined repeated identity.
LCM of 1 and 7 = 7

Total amount that Eva, Zoe and Barbara had is the next combined repeated identity.
LCM of 1 and 21 = 21 

Total amount contributed by Esther and Barbara
= 147 u + 14 u
= 161 u

161 u = 1449

1 u = 1449 ÷ 161 = $9

Total contribution by the four girls
= 168 u
= 168 x 9
= $1512

Answer(s): $1512