An 8 liter can filled with cooking oil weights 42kg. When 5 liters are emptied from the can,the can and the oil weight 27kg.What is the weight of the empty can?

Answer 1

weight of cooking oil per litre ---- x kg
weight of can ---- y kg

8x + y = 42
3x + y = 27
subtract them
5x = 15
x = 3

sub into 3x + y = 27
9 + y = 27
y = 18

the empty can weighs 18 kg

check:
8(3) + 18 = 42
3(3) + 18 = 27
my answer is correct