Question 1205563
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x,y,z = weight of the 3 chickens
The order doesn't really matter.


Add the weights pairwise
x+y = 10.6
y+z = 8.1
x+z = 6.1


Add straight down as the other tutor mentions to get
2x+2y+2z = 24.8
Divide everything by 2 to get
x+y+z = <font color=red>12.4</font>
Telling us that all three chickens combine to <font color=red>12.4 kg</font>


Since x+y+z = 12.4 and x+y = 10.6, we can replace the x+y block with 10.6 to isolate z
x+y+z = 12.4
10.6+z = 12.4
z = 12.4-10.6
z = <font color=red>1.8</font> is one of the individual weights.


Once we know z = <font color=red>1.8</font>, we can plug it into y+z = 8.1 and x+z = 6.1 to find y = <font color=red>6.3</font> and x = <font color=red>4.3</font> respectively. I'll leave the scratch work for the student to do.


Another way to find x is to use a similar trick that we did to isolate z.
Since x+y+z = 12.4 and y+z = 8.1 we can then say:
x+y+z = 12.4
x+8.1 = 12.4
x = 12.4-8.1
x = <font color=red>4.3</font>


Once you know 2 of the chicken's individual weights, you can plug them into x+y+z = 12.4 to find the missing variable.
As you can see, there's a few pathways you could take. Feel free to explore your favorite.


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Answers:
Total weight = <font color=red>12.4 kg</font>
Individual weights = <font color=red>4.3 kg</font> and <font color=red>6.3 kg</font> and <font color=red>1.8 kg</font>
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