The number of red precious stones used to make a necklace was 0.6 of the number of the white stones used. The number of green stones was 0.4 of the white stones. If 240 white stones were used, how many stones were used to make the necklace?
The number of red stones used to make the necklace is 0.6 * 240 stones = <<0.6*240=144>>144 stones.
50 stones are equally 0.2*240 stones,
The total number of green stones used is 0.4 * 240 stones = <<0.4*240=96>>96 stones.
To make the necklace, 240 + 144 + 96 stones = <<240+144+96=480>>480 stones were used. Answer: \boxed{480}.