A dishonest milkman professes to sell milk at cost price but he mixes water into the milk and therefore he gains by 35%. Find ratio of mixture to milk.

20  :  13

Gain is because of added water

CP  =  Milk Price

SP – CP  =  Water added (Profit)

35%  =  \(\frac{7}{20}\)       

Milk  :  Water   :     Mixture

  13    :     7      :          20

Mixture  :  Milk  =  20  :   13