Question 1199193
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When you mention something like "A tin of cookies is 630g", I'm assuming you mean the contents and the container itself combine to 630 grams.


c = weight of the container only
x = weight of all the cookies only when the container is full
weights are in grams


(1/2)x = container is half full
(1/2)x + c = 630


(7/9)x + c = 855


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We have this system of equations
(1/2)x + c = 630
(7/9)x + c = 855


I'll rearrange them to this
(7/9)x + c = 855
(1/2)x + c = 630


Subtract those equations straight down.
It allows us to solve for x.
(7/9)x - (1/2)x + c - c = 855 - 630
(7/9-1/2)x  = 225
(14/18-9/18)x  = 225
(5/18)x  = 225
x = 225*(18/5)
x = 810
The container can hold at most 810 grams of cookies.
This ignores the weight of the empty container itself.


Divide by 1000 to convert from grams to kilograms
810 g = (810/1000) kg = 0.81 kg


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Answer: 0.81 kg
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