There are two qualities of milk - Amul and Sudha having different prices per litre, their volumes being 130 litres and 180 litres respectively. After equal amounts of milk was removed from both, the milk removed from Amul was added to Sudha and viseversa. The resulting two types of milk now have the same price. Find the amount of milk drawn out from each type of milk.?

Hey guys as @Kunal Manchanda has wrote clear solution, I just thought it might help you to give a pdf for Formulas and tips on Mixtures and allegations. 

Let the price of Amul be X per litre and price for Sudha be Y per litre, and Z litre is removed and added
We further know that their price (in per litre) is same after the process.
So we get the equation.
{(130-Z)X +ZY}/(130-Z+Z) = {180-Z)Y +ZX}/(180-Z+Z)
Simplifying, we get
X - Z(X-Y)/130 = Y + Z(X-Y)/180

X-Y = Z(X-Y)/130 + Z(X-Y)/180
cancelling (X-Y), WE GET
1= Z/130 + Z/180
which gives the value of Z = 75.5 litres

75.49