Haria and Rasia have the same quantity of a mixture of water and milk having a ratio of water to milk as 3 : 7 and 2 : 8 respectively. They mixed both mixtures and went to the city to sell them. On the way to the city, there are several speed breakers by which 10% mixture gets spilled and the remaining mixture is sold at the cost price of milk. Find the percentage of overall profit they gain.