A bottle of lemonade is made in the ratio $2$ parts of lemon juice to $3$ parts of water. $80\text{ml}$ of lemon juice is added into the bottle, the ratio of lemon juice to water becomes $6$ to $5$. How much lemon juice was in the bottle at the beginning? 
Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Unit Rate and then the Total Value