Sorry for the spam guys, but i thought this would get more exposure here and I need some help with some maths.

Menthol DIY

can anyone work out how to get 20% of 50ml solution of menthol crystals when they have a density of 0.89g/cm cubed?

i think that this means that 1gram/ml doesn't quite apply as with water. it needs to be 1.something/ml which then needs to be multiplied by 10 to get the figure of 20% of 50ml.

Anyway i'm really special (i.e. not clever enough) and would really appreciate some help with this.