If 3 pots and 5 kettles cost $312...
and 5 pots and 3 kettles cost $232 (i.e. $80 less than $312)...

then 8 pots and 8 kettles cost $544 (think why)...

so 1 pot and 1 kettle cost $68...
and 3 pots and 3 kettles cost $204.

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3 pots and 5 kettles cost $312...
3 pots and 3 kettles cost $204...

The difference in the two scenarios is the 2 extra kettles. Because of the 2 extra kettles, the price difference is $108.

2 kettles = $108
1 kettle = $54

(and 1 pot = $68 - $54 = $14, because 1 pot + 1 kettle = $68)

Thanks for helping!