Question

A bucket when full of water weighs 18 kg.

half of the water is poured away.
the bucket and water now weighs 11 kg 
what is the weight of an empty bucket

Answer 1

18-11=7 to find out how much halve the water weight then subtract 7 from 11 11-7=4 so the emtpy bucket weighs 4 kg

Answer 2

`x-weights \ the \ bucket \\ y-weights \ the \ water \\\\ x+y=18 =>\boxed{x=18-y} \\ x+(y)/(2)=11 \\\\ 18^((2)-y^((2)+(y)/(2)=11^((2) \\\\ 36-2y+y=22 \\\\ 36-y=22 \\\\ -y=22-36 \\\\ -y=-14 \\\\ \boxed{y=14 kg} \\\\ x=18-14 \\\\ \boxed{x=4kg}`