# Question pertaining to Profit and loss, Proportion

I was trying to solve this question, couldn't get the start even sadly. The question is following :

Q: A dairyman pays dollar (couldn't get sign working) 6.40 per liter of milk. He adds water and sells the mixture at dollar 8 per liter, thereby making $37.5$% profit. The proportion of water to milk received by the customer is ?

Can anyone give me conceptual method to think of problem and hints to approach it?

-

Just give each unknown a variable and work your way through it. Get used to calculate this way.