Answer for this problem

Assume that initially the quantity of water is xL, which gives us the quantity of milk as "80-x"L. After taking out the mentioned qty of milk and water out, we are left with 0.7xL of water and 0.3*(80-x)L of milk.Also it is mentioned that the vessel was vacated by 55%, which means the final solution is of 0.45*80L = 36L, which can also be obtained by adding the final quantities of milk and water. Therefore, 0.7x+0.3(80-x) = 36 gives us the value of x=30L.

Small suggestion: Is it possible/feasible to remove negative marking for non multiple choice questions in your course?

Hi Himanshu, we actually dont have negative marking for Tita questions. Please let us know, if anywhere if negative marking is given for our tita questions. We will resolve it.