Red Shift is the term given to an object as it moves away from us, and thus exhibits a red colour

It's due to the fact that longer wavelengths (weaker) are Red, Yellow and Orange colours, and the wavelengths are stretched into longer forms during a Red Shift

Sale 1

http://www.tf2outpost.com/trade/27105708 Sold for 17 keys

B/O for L' was 17

X = 17

Keys https://gyazo.com/a933bb48694eb96e63d0b6bfe40db5aa http://backpack.tf/profiles/76561198053047207?time=1445065200&compare=1445670000

L' http://backpack.tf/item/3499712107

Sale 2

http://www.tf2outpost.com/trade/27482057 Sold for 2 keys + 15.4 keys of sweets

B/O for L' was 20

X = 2 + 15.4*0.9

X = 16

L' http://backpack.tf/item/3193516917

Stuff http://backpack.tf/profiles/76561198069668522?time=1448611200&compare=1448524800 https://gyazo.com/ccd8d4e3a7c0685b3aa91bf393760322

Sale 3

http://www.tf2outpost.com/trade/27464487 Sold with Blood Knife for Aussie Knife

B/O for Knife was 24

L' had no trade, presuming offered

X + 1 = 22

X = 21

Aussie http://backpack.tf/item/4281876866

L' http://backpack.tf/item/3193516917

Trade http://backpack.tf/profiles/76561198108956967?time=1447401600&compare=1448352000

Sale 4

http://www.tf2outpost.com/trade/26803680 Sold for Smoking Milk

B/O for L' was 21

X = 18.5*0.9

X = 17

L' http://backpack.tf/item/2267102074

Milk http://backpack.tf/item/798350717

Trade http://backpack.tf/profiles/76561198116676565?time=1446537600&compare=1446710400

Mini for Milk

http://backpack.tf/vote/id/5674f251dea9e9d3137f7680 18.5 keys, using 18.5